Prime Minister Tony Blair's Labor Party suffered its worst defeat in the modern history of local council elections across Britain in results announced Friday, a performance that analysts and politicians said in large part reflected popular disaffection with his support for the U.S.-led war in Iraq.

As the count continued, the BBC projected that Labor would finish a distant third with 26 percent of the vote nationwide, compared with 38 percent for the opposition Conservatives and 29 percent for the third-party Liberal Democrats. That would be the first time a party in power has finished third in these elections.

The party lost its hold on city councils in two former strongholds, Newcastle and Leeds in northeastern England, Labor's traditional heartland.

British voters traditionally use off-year local elections to send a protest message to the governing party, and Labor loyalists took heart from the fact that although their party was roundly defeated, the Conservative total was not large enough to suggest it would win the next general election, expected to take place in a year.

Paradoxically, some Laborites also took comfort from the fact that Iraq was a key factor, saying they hoped that by next year the issue will have faded.

Still, Labor leaders acknowledged the defeat was larger than they had expected. David Blunkett, one of Blair's senior cabinet ministers, pronounced himself "mortified" by the results and blamed them squarely on Iraq. "Some people felt it was the wrong policy," he told the BBC. "It split families, it split the Labor Party, it split friends."

The result, he said, was "a bad night for us, but not meltdown."

But the Liberal Democrat leader, Charles Kennedy, said Labor's defeat in the elections, which took place Thursday, reflected an overall loss of public trust in Blair and his government.

The results set off a new round of recriminations within Labor, with some party members calling for Blair to step down and others demanding that he apologize for supporting the war. Blair was attending Ronald Reagan's funeral in Washington and offered no immediate comment.

Peter Kellner, chairman of the London-based YouGov polling group, said the results were a serious blow to Labor. "Losing Newcastle is the equivalent of the Bronx going Republican -- it's almost inconceivable," he said.

But Kellner said that, based on past local election performances, the Conservatives had fallen well short of the total they needed to set themselves up for potential victory in next year's balloting, when voter turnout will be considerably higher. "The main opposition party traditionally needs to be at 45 or 46 percent to have a chance at victory," he said. "The Tories are stuck below 40, and that's not good enough."

Blair's party is widely forecast to suffer major losses in European Parliament elections, which also took place Thursday. Those results will not be announced until Sunday. But the impact is expected to be less clear because the Conservatives may also lose support to a new and virulently anti-European Union one-issue party, the U.K. Independence Party.

Labor's one bright spot was the victory of London Mayor Ken Livingstone, who rejoined the party this year after winning office as an independent in 2000. But the victory was tempered by the fact that Livingstone had expressed vehement opposition to the war in Iraq and may have lost votes by accepting the Labor endorsement.