Nigel Farage could be 'blocked' from becoming PM - 'Terrible news for Reform'

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.

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.