The broader debate has been spurred by the abuse of parliamentary expenses that set off the scrambling within Labor to dump Mr. Brown. Little in living memory has shocked Britain as much as revelations over the past month about members of Parliament of all parties who treated the public purse as a private piggy-bank.  Mr. Brown has said that “cleaning up politics” is part of the reason he has resolved to stay in office. And for the moment, like a boxer rebounding from a succession of knockdowns, he has shrugged off the one-two combination of Labor’s defeat in the European elections, which gave the party less than 16 percent of the nationwide vote in results that became known on Monday, and dismal local election results last week, which gave Labor only 23 percent, another record low.  Political leaders acknowledge that the crisis goes far beyond the expense abuses. All of the major party leaders have shifted into populist mode, promising a top-to-bottom overhaul of Britain’s parliamentary system, with reforms to make the government more accountable to Parliament, and Parliament more responsive to the public will.  There has even been discussion of adopting a written constitution, a step that could abruptly curb the powers of government here, because a prime minister with a large parliamentary majority — Mr. Brown, for the past two years — is essentially in the position of an elected dictator, free of many of the constraints that face American presidents.  But the question haunting politics here is why it took so long for the expenses scandal to awaken the political establishment. The major political leaders have all been unable to explain how they tolerated abuses that were so widespread, and why they reacted with blustering dismay only when the abuses became public in three weeks of exposés in The Daily Telegraph.  The answer seems to be that the abuses involved many of the party leaders’ most powerful political allies, and touched them personally, though the decisions by Mr. Brown and David Cameron, the Conservatives’ leader, to claim so-called second-home expenses appear to have been lawful. Still, they are left with a scandal that has exposed the political class here in much the same way that the novels of Charles Dickens exposed the moral decay of Victorian England.  It is partly because of the plague-on-all-your houses public mood that Mr. Brown is thought capable of hanging on until the general election. He has said that Labor’s meltdown at the polls is a symptom of a broad public disenchantment with traditional politics, not a repudiation of him personally, and that the party will recover in the polls when the fury over expenses recedes. But he continues to endure defections. After 10 of 33 ministers who can attend cabinet meetings quit in staged succession over the previous week, Jane Kennedy, the environment minister, resigned Monday, saying she could no longer support Mr. Brown because of a culture at 10 Downing Street of “orchestrated undermining” and “smears” of his Labor foes.  Yet an analysis of the weekend’s election results left the prime minister with at least some ammunition. Dismal as Labor’s showing was in the European Parliament voting, there was not much in the results for the Conservatives to crow about, either. They received 29 percent of the vote, only one percentage point more than in the last European vote, in 2004, with the 7 percent fall in Labor’s vote going mainly to splinter parties. That suggested, British political commentators said, that the Conservatives’ political fortunes hung on more than the public disillusionment with Mr. Brown.  John F. Burns reported from London, and Alan Cowell from Paris  A version of this article appears in print on , on Page A13 of the New York edition with the headline: Hit Hard Again, Brown Stays in the Ring. Order Reprints| Today's Paper|Subscribe
After the Labor Party’s worst showing in elections for the European Parliament, Britain’s prime minister pledged to abandon the “bunker mentality.”