LONDON - Prime Minister Gordon Brown faced a political nightmare yesterday with the resignation of his fourth government minister in two days.

The departures came on the eve of local and European elections in which his Labor Party appeared headed for its worst-ever defeat.

"It gives the appearance that the rats are leaving a sinking ship," said Alan Finlayson, an expert on Labor.

Analysts said Brown could possibly be forced out after months of anemic popularity ratings and more recently a parliamentary expense-abuse scandal that also has touched members of his cabinet.

Brown has rejected suggestions to quit, and most analysts agreed he would be viscerally opposed to stepping aside after waiting nearly a decade to take over from Prime Minister Tony Blair.

If Brown left now, after less than two years in office, he would be one of the shortest-serving British leaders in modern history.

"But he is resilient and tough, and he's still more likely to stay than to go," said Tony Travers, a professor of political science at the London School of Economics.

The situation became more chaotic yesterday when a longtime Brown ally and cabinet member, Communities Secretary Hazel Blears, resigned unexpectedly. Her departure followed announcements Tuesday that Home Secretary Jacqui Smith and two lower-ranking cabinet ministers plan to step down.

All had been caught up in the expenses scandal. Blears failed to pay taxes on a second home on which parliamentary rules allowed her to claim expenses. She later paid back $21,000 but said she had done nothing wrong.

Distance between Blears and Brown grew when Brown called her actions "totally unacceptable." Analysts said Blears appeared to take her revenge by making her high-profile exit at the worst possible moment - on the day before key elections.

Brown's popularity among British voters has been steadily declining because of a widespread perception of disarray and lack of decisiveness.

Britain's rising unemployment and other severe economic woes have added to Brown's problems, though he has been viewed as providing strong leadership on the global financial crisis.

Public anger and disillusionment with Brown reached new peaks with the expenses scandal. Although much of the scandal has centered on legislators' expenses related to second homes, other expenses have included a Conservative Party member who expensed the cleaning of the moat around his country home and a Labor MP who sought government reimbursement for 5 pounds (about $8.25) he placed in a church offertory.

"I think the word scandal is almost demeaning - it's much larger than that," said Julia Clark, head of political research at Ipsos MORI, a survey research organization, whose polling shows that 75 percent of Britons don't trust politicians to tell the truth.

Although expense offenders have come from all parties, Brown's handling of the crisis has been widely criticized as slow and tepid.

Brown "has never gotten over the label that he is a ditherer," said Nicola McEwen, a senior lecturer in politics at the University of Edinburgh.

The expense scandal was the last straw for even some of Brown's staunchest supporters, including the Guardian newspaper.

"It is time to cut him loose," it editorialized yesterday.

Voters will cast ballots today for the British representatives to the European Parliament and for local councils across the country. Recent polls have shown Labor will do terribly, with one giving it just 18 percent popularity, the lowest ever recorded.

Brown responded that his government had been working to clean up the expenses system and steer the economy out of recession. He accused his opponents of attacking him politically without offering substantive policies.