LONDON — British Prime Minister Gordon Brown clung fiercely to his job today, defying calls from some within his beleaguered Labour party to resign.

Brown told reporters he never even considered resigning, instead announcing a Cabinet reshuffle he hopes will help restore his fortunes. Brown has been badly stung by a scandal over British lawmakers’ expenses, a string of top-level resignations and catastrophic results expected in local elections.

“I have the determination to take this country through the most difficult of economic times, and this is what I am doing,” he said. “I will get on with the job and I will finish the work.”

Brown, who some legislators view as the key obstacle to the party’s hopes of avoiding defeat in the next national election, promoted key allies to his inner circle in a bid to block efforts to oust him from his post.

Work and Pensions Secretary James Purnell, a 39-year-old fast-rising star in Brown’s government, dramatically quit late Thursday and urged Brown to step aside. “I now believe your continued leadership makes a Conservative victory more, not less likely,” he told Brown in a resignation letter.

Defense Secretary John Hutton, who was regarded as one of the Cabinet’s best performers, announced today he was quitting his post — the 11th surprise resignation in four days. But he offered Brown his support — mitigating the impact of his departure.

In a dig at those who jumped ship, Brown said today that he was filling his Cabinet with people “who will not walk away from their responsibilities when the going gets tough.”

But even as Brown announced his new lineup, news broke of another resignation: Caroline Flint, his Europe minister, is leaving her post. Brown was at pains to emphasize that he was still in control — while defending himself against charges that he was ignoring the will of his party.

“I’m not arrogant, and I’m never complacent,” Brown said.

Brown also promised to introduce an independent regulatory body to oversee lawmakers’ expense claims, whose publication has deeply embarrassed parliamentarians and badly eroded support for Labour.

Hutton’s deputy, Armed Forces Minister Bob Ainsworth, replaced him, the defense ministry’s Web site said.

Brown spent much of today huddled in a basement office in his official Downing Street residence, shuffling Post-it notes as the 58-year-old Scot finalized his Cabinet shake-up with a few close aides.

Outside, critics lambasted Brown, as results of British local elections held Thursday showed a new collapse for support in the party which has held power since 1997. The opposition Conservatives won key town and city council seats from Brown’s Labour, making inroads into the government’s former strongholds in northern and central England.

Though Brown has gained praise overseas for his handling of the global economic crisis, he trails the main opposition Conservative Party in opinion polls and is widely expected to lose the next national election.

His government has suffered the most in a scandal over lawmakers’ expense claims, blamed for failing to reform a system that allowed legislators from all parties to charge for items like horse manure, porn movies and repairs to the moat of a country mansion.

Alan Johnson, the affable health secretary — who is often mentioned as a replacement for Brown — urged colleagues to unite behind the prime minister despite the results. Johnson was appointed home secretary as a reward for his loyalty.

“I continue to believe that Gordon Brown is the best man for the job,” Johnson said in a statement. “It is vital now, more than ever, that we unite for the sake of the party and the government.”

Treasury chief Alistair Darling remained in place, despite concern over his expenses claims. Darling has repaid some money after he acknowledged mistakes in his claims and has faced criticism over his manipulation of the housing allowance system.

Alan Sugar, a brash businessman and host of the British version of “The Apprentice” television show, was likely to be made a member of the House of Lords to allow Brown to hand him a roving role to promote entrepreneurship and help stimulate Britain’s economy.