Voters in Caerphilly on Thursday provided a blueprint for how rival parties are likely to try and block Nigel Farage’s path to Downing Street, with one expert calling it “terrible news” for the Reform UK leader. The Senedd by-election in the Welsh constituency on Thursday saw Plaid Cymru secure a comfortable victory, taking 47.4% of the vote – an increase of 19 percentage points from its performance in the seat at the 2021 election.
Reform UK finished second with 36%, a strong showing consistent with its recent national polling around 30%, but insufficient to win. Labour, which has held the seat continuously since 1918, suffered its worst by-election defeat in Welsh history, managing just 11 per cent—a drop of 35 points. The Conservatives recorded their lowest by-election share ever, at 2%. Turnout was approximately 30%. The result represents an astonishing success for Plaid Cymru and a stark warning to Labour, while highlighting potential limits to Reform’s rise. If Plaid’s advance were replicated across Wales in the 2026 Senedd election, the party would achieve a record 40% of the vote share.
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Reform UK leader Nigel Farage (Image: Getty)
Plaid Cymru leader Rhun ap Iorwerth walks to the Senedd with Lindsay Whittle (Image: Getty Images)
Plaid’s candidate, Lindsay Whittle, a councillor with 50 years’ experience who was contesting the seat for the 14th time, benefited from personal popularity. The outcome strengthens the position of Plaid leader Rhun ap Iorwerth to become Wales’s next First Minister, likely heading a minority government under the assembly’s new proportional representation system.
Labour’s collapse underscores growing voter impatience after 26 years in devolved power. The party’s Westminster vote share in Wales fell by four points last year, to 37%—no higher than in 2010, when Gordon Brown was ousted.
Issues including lengthy NHS waiting lists have eroded support, compounded by dissatisfaction with Sir Keir Starmer‘s UK government. Britain-wide polls now place Labour at around 23%, though some trackers show it dipping as low as 20%, raising the prospect of a third-place finish in the 2026 Senedd contest.
Reform UK had hoped to replicate its victory in the May Runcorn by-election, but Caerphilly showed that 30% may not suffice against a consolidated opposition. The party’s support draws heavily from Brexit backers concerned about immigration, a niche that analysts say may cap its broader appeal.
As Sir John Curtice, professor of politics at the University of Strathclyde and a leading election forecaster, noted in analysis for The Times, the result highlighted tactical voting’s role in uniting progressive voters against Reform, contrasting it with Runcorn where weaker coordination allowed Farage’s party to prevail. He described such fluidity under first-past-the-post (FPTP) as a “potent weapon” in vulnerable Labour areas.
Tactical voting occurs when electors back their second-preferred candidate to defeat a mutual opponent, rather than splitting the opposition vote among like-minded parties. In FPTP systems, which award seats to the candidate with the plurality of votes, this strategy can have outsized effects by concentrating anti-establishment or anti-populist sentiment into winnable contests.
In Caerphilly, it played out as supporters of Labour, the Liberal Democrats and Greens – who each polled under 2% – shifted en masse to Plaid Cymru, transforming a multi-party field into an effective two-way race which Reform could not win.
Looking ahead to the 2029 general election, experts warn that scaled-up tactical voting could systematically thwart Reform’s ambitions. With Reform’s support dispersed nationally – often pulling from disaffected Conservatives without reciprocal loyalty – progressive pacts could consolidate 40-50% of the left-of-centre vote in key marginals, denying Farage the 326 seats needed for a majority.
Ben Walker, politics editor at the New Statesman, described the Caerphilly outcome in a post-result video as a “proof of concept” for such anti-Reform alliances. He said: “High turnout amplified the effect. Without coordination, Reform could capitalise on Labour’s weaknesses; instead, this demonstrates how pacts can deny them breakthroughs on a larger scale.”
Academic research bolsters this prognosis. Professor Jane Green of the University of Oxford, co-director of the British Election Study, demonstrated in a January 2025 analysis how tactical anti-Conservative efforts in 2024 yielded the Liberal Democrats 72 seats from a vote share akin to Reform’s paltry five, due to vote fragmentation on the right.
Dr Stephen Fisher, associate professor of political sociology at the University of Oxford, documented in June 2024 polling data a 0.5-point increase in mutual support between Labour and Liberal Democrat voters since 2019—contrasted with declining affinity between Conservatives and Reform UK voters. He argued this asymmetry could persist and widen under sustained anti-Farage mobilisation.
Professor Tim Bale of Queen Mary University of London, in a September 2025 interview, emphasised Reform’s structural hurdles: Mr Farage’s divisive image and the party’s lack of governing experience render it vulnerable to “contingent” voter backlashes, especially if incumbents address economic pressures.
The Caerphilly template could inspire nationwide coordination. Poppy Coburn, associate editor at The Telegraph, outlined in a recent video explainer how alliances across Labour, the Liberal Democrats, Greens, Plaid Cymru and the SNP might leverage FPTP’s mechanics and common antipathy to Farage’s brand to block Reform majorities. She concluded: “That’s terrible news for Nigel Farage.”
Conservative support has collapsed amid Reform’s surge, but Labour’s erosion extends leftward, with Plaid inflicting heavy damage here. Both established parties face an existential recalibration to preserve their grip on British electoral politics.
Nigel Farage Could Be ‘Blocked’ From Becoming PM – ‘Terrible News for Reform’
Nigel Farage’s ambition to become Britain’s next prime minister has faced a new question: could tactical voting prevent Reform UK from translating its support into enough parliamentary seats to form a government?
The possibility was highlighted by polling published in August 2026, which examined attitudes towards a hypothetical Reform UK government and the willingness of voters opposed to the party to vote tactically.
The findings did not show that Farage was automatically prevented from reaching Downing Street. Instead, they demonstrated a potential electoral obstacle facing Reform UK: the party could win substantial support nationally while still encountering difficulties in individual constituencies if opponents coordinate their votes.
That distinction is important because Britain’s first-past-the-post electoral system means that winning a large national vote share does not necessarily translate directly into a parliamentary majority.
The tactical voting question
Research commissioned by HOPE not hate and conducted by Focaldata found that 43 percent of respondents would be unhappy with the prospect of a Reform UK government led by Farage. Among those voters, 69 percent said they would be prepared to vote tactically for whichever candidate was best placed to prevent a Reform candidate from winning in their constituency.
The figures immediately generated discussion about whether anti-Reform tactical voting could become a significant factor at a future general election.
For Reform, the issue is straightforward in electoral terms. A constituency can be won with a plurality rather than a majority. If opposition parties divide their votes between Labour, Conservatives, Liberal Democrats, Greens or other candidates, Reform could win even without securing half of the vote.
Conversely, if voters opposed to Reform concentrate their support behind one challenger, a Reform candidate could lose despite the party having a substantial national vote share.
This is one of the central uncertainties surrounding Britain’s increasingly fragmented political landscape.
Why Reform faces a different electoral environment
Reform UK has undergone a major transformation since Nigel Farage returned to frontline politics.
The party made significant gains in local elections and established itself as a major challenger to Labour. Yet its national polling position changed during 2026 after Andy Burnham became prime minister.
A September YouGov poll found Labour on 23 percent, with Reform UK and the Conservatives both on 21 percent.
That was a markedly different picture from the period when Reform was regularly polling above 30 percent.
Sky News election analyst Professor Rob Ford noted in September that Reform’s average support across nine pollsters had fallen substantially compared with the previous year. He also observed that projections suggesting a Commons majority for Reform had become much less common.
These figures do not determine the outcome of a future election. They do, however, show why the tactical voting debate has become more relevant.
A party that is consistently polling in the mid-20s faces a different mathematical challenge from one polling comfortably above 30 percent.
The constituency problem
The Focaldata research highlighted the importance of individual constituencies.
According to the report, a Survation MRP model identified 95 “fragile Reform” seats where Reform was projected to be within three percentage points of its nearest rival. It also identified 199 constituencies where Reform was projected to win because opposition votes were divided among multiple parties.
MRP, or multilevel regression and post-stratification, is a modelling technique that estimates voting patterns across individual constituencies.
Such projections should not be confused with actual election results.
They are based on assumptions about voting behaviour and can change significantly as public opinion changes, candidates are selected and campaigns develop.
Nevertheless, the figures illustrate the structural challenge created by Britain’s electoral system.
Reform can have a strong national vote while still depending heavily on how its support is distributed geographically.
If its voters are concentrated in constituencies where it already has a clear lead, the party could convert votes into seats efficiently. If its support is spread more evenly, it could receive millions of votes without winning enough constituencies to form a government.
Farage’s personal position
The debate also concerns Farage himself.
Reform remains strongly associated with its leader, and polling suggests that his personal standing matters considerably to the party.
YouGov found in September that only 19 percent of Britons viewed Farage as a “prime minister in waiting”, while 66 percent disagreed. The proportion seeing him in that role had fallen seven points since June.
At the same time, Farage remains considerably more popular among Reform supporters than among the public as a whole.
That creates a complicated political picture.
His profile is an important asset for Reform because he provides national recognition and a clear public identity for the party. But his personal ratings can also become an electoral constraint if voters who might otherwise consider Reform are strongly opposed to Farage himself.
Ipsos polling conducted in late August found that 26 percent of Britons viewed Farage favourably while 54 percent viewed him unfavourably. When respondents were presented with a direct choice between an Andy Burnham-led Labour government and a Farage-led Reform government, 50 percent preferred Burnham’s government compared with 29 percent for Farage’s.
Again, this was a survey question rather than an election result.
It nevertheless demonstrates that support for Reform UK and personal support for Farage are not identical.
Reform’s supporters remain loyal
The picture is not simply one of declining enthusiasm for Farage.
Research among Reform members has shown a much stronger level of loyalty.
A Lord Ashcroft poll of 850 Reform members in June found that four out of five wanted Farage to remain leader even if Reform did not enter government after the next general election. Only 13 percent said he should step down in that circumstance.
This highlights an important distinction between the party’s membership and the wider electorate.
Within Reform, Farage continues to occupy a central position. Potential successors such as Zia Yusuf and Richard Tice have attracted attention, but Farage remains the dominant figure.
The question is therefore not whether Reform currently has a leader who is widely recognised. It clearly does.
The question is whether Farage’s popularity within Reform can be translated into enough support across the wider electorate and, crucially, enough constituency victories.
The role of the other parties
Tactical voting would require voters to make decisions based not only on their preferred party but also on which candidate has the strongest chance of defeating Reform locally.
That could produce complicated outcomes.
A Labour voter in one constituency might decide that the Conservative candidate is the strongest challenger to Reform. In another constituency, a Conservative voter might conclude that Labour is better placed. In a different seat, the Liberal Democrats or Greens could be the main challenger.
This makes tactical voting highly localised.
There is also no guarantee that voters will follow tactical recommendations. Political parties have different policy positions, and supporters may prefer to vote for their first-choice candidate even when another candidate has a greater chance of defeating Reform.
The possibility of tactical voting therefore represents a potential factor rather than a guaranteed electoral mechanism.
Reform’s response
Reform has consistently argued that it is capable of breaking the traditional political pattern.
Farage has positioned the party as an alternative to both Labour and the Conservatives, while Reform’s campaign has focused heavily on immigration, taxation, public services, regulation and national sovereignty.
The party’s supporters can also point to its electoral expansion as evidence that its appeal extends beyond a narrow protest vote.
But the political environment in 2026 is different from that of the previous year.
Andy Burnham’s arrival in Downing Street altered Labour’s position in the polls, while Kemi Badenoch’s Conservatives have also regained some support from voters who had previously considered Reform.
YouGov’s September figures showed the Conservatives level with Reform at 21 percent, while Labour remained slightly ahead on 23 percent.
That three-way competition makes tactical voting more difficult to predict.
What “blocking Farage” really means
The phrase “blocking” Farage from becoming prime minister can therefore sound more dramatic than the underlying electoral mechanism.
There is no separate parliamentary rule preventing Farage from becoming prime minister if he leads a party capable of commanding the confidence of the House of Commons.
The potential obstacle is electoral.
If Reform wins enough constituencies to command a Commons majority, or becomes the largest party and can secure sufficient parliamentary support, Farage could become prime minister.
If Reform falls short because competing parties successfully retain enough seats through their own support or tactical voting, another party could form the government instead.
The outcome would depend on the distribution of seats, not simply on Farage’s personal popularity.
A challenge that goes beyond one election
The tactical voting debate is therefore part of a much larger transformation in British politics.
For decades, Labour and the Conservatives dominated Westminster elections. Reform’s rise has disrupted that pattern, but the emergence of a strong third force also creates new strategic calculations for voters and competing parties.
The more fragmented the electorate becomes, the more important constituency-level dynamics can become.
For Reform UK, this creates both opportunities and risks.
The party has demonstrated that it can attract substantial national support and win seats. But its route to government depends on converting that support into a sufficiently large parliamentary presence.
For Farage personally, the challenge is even more direct. His political future is closely connected to Reform’s ability to broaden its appeal beyond its existing base.
The August polling did not prove that tactical voting will prevent him from becoming prime minister. Nor did it establish that Reform is destined to enter government.
It showed something more specific: a significant proportion of voters opposed to Reform say they are willing to consider tactical voting, and constituency modelling suggests that fragmented opposition could be an important factor in some seats.
As Britain moves toward its next general election, both Reform and its opponents will therefore have to pay close attention to the geography of support.
For Farage, national headlines and polling percentages will only tell part of the story.
The decisive question will ultimately be how those votes are distributed across hundreds of individual constituencies — and whether voters choose their preferred party or attempt to influence which candidate finishes first.
That is why the prospect of tactical voting has become such an important part of the debate surrounding Farage’s ambition to reach Downing Street.