LONDON (AP) — British Prime Minister Keir Starmer pledged Monday to prove the "doubters" in his own party and among the electorate as a whole wrong as he tries to fight off demands to step down after devastating local election results for his Labour Party.

Starmer argued that he will "face up to the big challenges" and restore hope to the country, in part by forging closer ties with the European Union, six years after the U.K.'s acrimonious departure from the bloc.

"I know I have my doubters and I know I need to prove them wrong, and I will," Starmer said during a speech in London. He vowed to prove to millions of people "tired of a status quo that has failed them" that the government is on their side.

He said Labour is in "a battle for the soul of our nation," and warned Britain will go down "a dark path" if Reform UK, the anti-immigration party led by Nigel Farage, comes to power.

Starmer is warned it's his last chance

Starmer's position remains precarious. Labour lawmaker Catherine West, who had vowed to trigger a leadership challenge if the speech didn't mark a major turning point, said she would hold off for now, though she urged Starmer to resign by September. Dozens of other lawmakers also have urged him to announce a departure date, with the number ticking up in the hours after the speech.

Labour has been plunged into gloom by heavy losses last week in local elections across England and legislative votes in Scotland and Wales. The elections have been interpreted as an unofficial referendum on Starmer, whose popularity has plummeted since he swept to power in a landslide less than two years ago.

Former Deputy Prime Minister Angela Rayner, a powerful lawmaker often seen as a potential challenger, said the party is facing its "last chance" to change.

Rayner did not explicitly call for Starmer to quit, but accused him of presiding over "a toxic culture of cronyism" and said the government must "stay true to Labour and social democratic values" and ease the cost of living for working people.

Starmer's government has struggled to deliver promised economic growth, repair tattered public services and ease the cost of living, and been hamstrung by repeated missteps and policy U-turns on issues including welfare reform. He has been further hurt by his disastrous decision to appoint Peter Mandelson, a scandal-tarnished friend of Jeffrey Epstein, as Britain's ambassador to Washington.

READ MORE: British voters cast ballots in local elections seen as a verdict on Keir Starmer's leadership

Last week's elections saw Labour squeezed from both right and left, losing votes to both Reform UK and the "eco-populist" Green Party. The result reflects the increasing fragmentation of British politics, long dominated by Labour and the Conservatives.

Starmer hopes to regain more momentum with an ambitious set of legislative plans to be set out in a speech Wednesday by King Charles III at the State Opening of Parliament.

On Monday he told an audience of party lawmakers and activists that the government will take control of Britain's energy, economic and defense security and make the country fairer. He announced plans to nationalize what is left of the once-mighty British Steel, a move that could save some industrial jobs in an area where working-class voters have deserted Labour for Reform UK.

Starmer also pledged to put Britain "at the heart of Europe" and forge closer ties with the 27-nation EU. Farage, who spearheaded the Brexit campaign, and Reform UK oppose any move to get closer to the EU.

Brexit has been a drag on the British economy, and President Donald Trump's "America First" economic and foreign policy has spurred Britain to seek closer defense, security and economic cooperation with its European neighbors.

Starmer's government has already moved to ease trade restrictions with the EU, and he said he will secure a youth mobility deal so young people can spend a few years working across the continent.

Labour supporters are largely anti-Brexit, which failed to deliver the benefits its backers promised. But Starmer has been reluctant to reopen a debate that bitterly divided the country. He has ruled out seeking to reenter the EU, or to rejoin the bloc's customs union or single market, things that would make a big economic difference.

Rivals weigh making a move

None of the high-profile Labour politicians considered potential challengers to Starmer — including Rayner, Health Secretary Wes Streeting and Greater Manchester Mayor Andy Burnham — has yet called for him to resign.

British politics allows parties to change leader midterm without the need for a new election.

West, who had threatened to run against Starmer for the Labour leadership if he didn't give a barnstorming speech, said she would instead ask fellow lawmakers to back a timetable for a new leader to be elected by September.

"What is best for the party and country now is for an orderly transition," she said.

Some party colleagues spoke in support of West's call.

"I don't think we saw a plan from the prime minister this morning in order to implement the kind of change that this country needs, and I therefore think it's time for us to look for new leadership," lawmaker Chris Curtis told Sky News.

But some who attended Starmer's speech said kicking out the man who led them to victory in 2024 would be counterproductive.

"You can't be changing prime ministers two years in," said Kevin Craig, a former local councilor in London. "It's really important we stay grown-up now."