Keir Starmer Humiliated by Green By-Election Victory
Keir Starmer has suffered one of the most damaging electoral setbacks of his premiership after the Green Party overturned a long-standing Labour majority in the Gorton and Denton by-election. The result was not merely another difficult night for the governing party. It was a historic breakthrough for the Greens and a powerful warning that Labour’s political coalition is becoming increasingly vulnerable from both the left and the right.
The scale of the defeat makes the result particularly painful for Starmer. Labour had held the constituency continuously since 1935, yet the party was pushed into third place. Green candidate Hannah Spencer won 14,980 votes, defeating Reform UK in second place by 4,402 votes, while Labour finished third on 9,364 votes. The Greens therefore achieved their first-ever Westminster by-election victory and gained their fifth MP.
For a prime minister who entered Downing Street promising to restore Labour’s political credibility, this is an extraordinary reversal.
The significance of the result goes beyond the loss of one parliamentary seat. Gorton and Denton demonstrated that Labour is facing a problem on two fronts. Reform UK has been taking support from voters who are angry about immigration, economic pressures and the direction of the country, while the Greens are attracting voters who believe Labour has moved too far from progressive politics.
That leaves Starmer confronting a difficult political question: exactly who is Labour now supposed to represent?
The party’s enormous 2024 general-election majority created an impression of strength. Labour won 411 seats and returned to government after fourteen years of Conservative rule. Yet the electoral foundation beneath that majority was much less secure than the size of the parliamentary majority suggested. Labour received around 34% of the vote, meaning a relatively modest share of the electorate delivered a huge Commons advantage under Britain’s first-past-the-post system.
The Gorton and Denton result has exposed that vulnerability in dramatic fashion.
For the Greens, meanwhile, the victory represents a breakthrough that could transform the party’s ambitions. Winning a parliamentary by-election is psychologically different from gaining council seats. It demonstrates that the party can win Westminster representation in a direct electoral contest and gives its activists a powerful example to point towards in future campaigns.
The victory also suggests that progressive voters are increasingly willing to punish Labour rather than automatically support it.
That is perhaps the most uncomfortable lesson for Starmer.
Labour traditionally depended upon a broad coalition: working-class voters, trade union supporters, socially liberal urban voters, younger people and sections of Britain’s ethnic minority communities. Maintaining that coalition was always difficult because these groups do not necessarily agree on every major issue.
Starmer’s strategy after taking over Labour was to move the party towards the political centre and present it as a responsible alternative to Conservative government. That strategy helped Labour win the 2024 general election. But the Gorton and Denton result suggests that some voters who supported Labour as the lesser of two evils may now be willing to look elsewhere.
The Greens have identified precisely this opportunity.
Their campaign focused on voters dissatisfied with Labour, including those who wanted a stronger position on environmental issues and progressive social policy. The by-election was widely regarded as a three-way contest involving Labour, Reform and the Greens, making the eventual result particularly significant.
In other words, Labour was not simply defeated by an opposition party. It was squeezed from both directions.
That creates a strategic nightmare.
If Starmer responds by moving further to the left, he risks losing voters who have become attracted to Reform or who prefer a more economically conservative approach. If he moves towards the centre, he risks allowing the Greens to capture even more progressive voters.
There may be no easy route back to the broad coalition that produced his 2024 victory.
The political consequences are therefore potentially much larger than the seat itself.
A by-election can act as a laboratory for national politics. Turnout, candidates and local circumstances are different from those of a general election, so one result cannot automatically be extrapolated across the country. Nevertheless, dramatic swings can reveal changes in voter attitudes that established parties ignore at their peril.
Gorton and Denton was particularly revealing because Labour did not merely lose a narrow contest. The party fell to third place behind both the Greens and Reform UK.
That should concern Labour strategists enormously.
The rise of Reform is already forcing the party to confront questions about immigration, national identity, public spending and working-class voters. The Green victory adds another layer of difficulty by demonstrating that Labour can also lose support among voters who consider themselves progressive.
Starmer therefore risks finding himself in the political equivalent of a vice.
On one side is Nigel Farage and Reform UK, presenting themselves as the voice of voters who believe Westminster has become too liberal, too distant and too unwilling to address concerns about borders and national identity. On the other is the Green Party, arguing that Labour has become too cautious and insufficiently radical.
Between them sits Labour.
The question is whether Starmer can persuade enough voters that his party remains the only credible national alternative.
His response to the result has reportedly been to tell Labour MPs that the Green victory was a temporary setback rather than evidence of a fundamental realignment. That may be politically understandable. No prime minister wants to concede that a by-election defeat represents the beginning of a larger collapse.
But political leaders ignore warning signs at their own risk.
The result was described as seismic by political scientist John Curtice, underlining the historic nature of the Greens’ achievement. It overturned a Labour majority of more than 13,000 votes from the 2024 general election and produced one of the most striking by-election reversals in recent British political history.
For Green leader Zack Polanski and his colleagues, the message is obvious: Labour’s voters are no longer guaranteed to remain loyal.
The Greens can now argue that voting Green is not merely symbolic. They have demonstrated that the party can win a parliamentary constituency, even in an area with a long Labour tradition.
That could have consequences far beyond Gorton and Denton.
If Green candidates begin attracting significant numbers of Labour voters in urban and university-heavy constituencies, Labour could find itself fighting defensive battles in seats that were previously regarded as safe. At the same time, Reform could threaten Labour in parts of northern England and the Midlands.
The first-past-the-post electoral system makes this particularly dangerous. A party does not need to lose half its voters to lose a seat. If its support is divided between several challengers, relatively modest shifts can produce dramatic changes in parliamentary representation.
That is precisely what happened in Gorton and Denton.
Yet the Greens also face their own challenge. A spectacular by-election victory creates expectations. The party must now prove that the result was not simply a unique combination of local circumstances, Labour’s unpopularity and tactical voting.
If the Greens can reproduce this success elsewhere, British politics could be entering a period of genuine four- or five-party competition. If they cannot, Gorton and Denton may ultimately prove to have been an exceptional result.
For Starmer, however, waiting to find out may be dangerous.
The lesson from the by-election is not necessarily that Labour is finished. It is that Labour can no longer assume that its traditional supporters have nowhere else to go.
The party’s 2024 victory was built on voters wanting change after fourteen years of Conservative government. But governing is different from campaigning. Once Labour becomes responsible for difficult decisions, disappointed supporters have an alternative available to them.
That is the new political reality Starmer must confront.
The prime minister can dismiss the result as a one-off, or he can treat it as a warning. He can argue that only Labour can govern effectively, or he can ask why voters who once supported Labour are increasingly attracted to its rivals.
The second approach would be considerably harder—but potentially much more valuable.
Because the real humiliation for Starmer is not simply that the Greens won.
It is that Labour’s opponents now believe they have discovered a formula for beating the party in places where victory once seemed almost impossible.
Reform has already demonstrated its ability to break through Labour’s traditional support. The Greens have now shown that the party can be challenged from the opposite direction. The Conservatives, Liberal Democrats and smaller parties will also be watching carefully for opportunities.
Britain’s political map is changing.
For years, British politics was dominated by two major parties. Today, voters appear increasingly willing to move between several competing alternatives. Loyalty is weaker, protest voting is stronger and political identities are becoming more complicated.
Gorton and Denton may therefore be remembered not simply as a Green victory, but as another milestone in the fragmentation of British politics.
For Keir Starmer, that should be a wake-up call.
A prime minister does not need to win every by-election. But when a party that has held a constituency for generations suddenly falls to third place, the result deserves more than a shrug.
The Greens have made history. Reform has strengthened its position. Labour has been pushed aside.
The question now is whether Starmer can reverse that trend before today’s by-election humiliation becomes tomorrow’s national political crisis.