As Tony Blair tries to turn public attention to domestic affairs, the latest kidnapping crisis in Baghdad has forced the British prime minister once again to wrestle with the consequences of Britain's participation in the Iraq war.

The abduction of a British civil engineer, Kenneth Bigley, and the threat by his captors to kill him have thrust Iraq back to the top of the political agenda here and riveted the public. Television and radio news Thursday led with tearful pleas to the kidnappers from Bigley's 86-year-old mother, who lives in Liverpool, and from his wife in Bangkok to spare his life.

Meanwhile, Paul Bigley, the hostage's brother, accused the United States of sabotaging efforts by Iraqi officials to release one of the female prisoners whose freedom has been the kidnappers' central demand.

The front page of every British newspaper Thursday morning featured Kenneth Bigley's emotional appeal to Blair to intervene, made in a video posted on the Internet the night before.

"KEN: SAVE ME, TONY" was the lead headline in the Sun, the country's largest-selling tabloid. "PLEASE HELP ME, MR BLAIR. I DON'T WANT TO DIE. I DON'T DESERVE IT," said the Daily Telegraph's headline.

British officials confirmed that Blair had seen a transcript of the video, but they would not comment on his reaction. Foreign Secretary Jack Straw told reporters at the United Nations that his government would not budge from its position of refusing to bargain with the kidnappers. "We continue to do everything we can," he said, "but it would be idle to pretend there's a great deal of hope."

Bigley, 62, was abducted last Thursday along with two Americans from their residence in the Mansour neighborhood by gunmen apparently working for the Monotheism and Jihad group headed by a Jordanian-born Muslim radical, Abu Musab Zarqawi. The two Americans were beheaded this week after authorities failed to meet their captors' demands to release all female Iraqi prisoners.

Analysts said British public opinion, which became hardened against terrorist attacks during the bombing campaign by Irish nationalists in the 1970s, '80s and '90s, would support Blair's refusal to bargain. "The particular circumstances of this poor man will have little or no direct impact on domestic political opinion," said Peter Kellner, chairman of the public polling organization YouGov.

Still, Kellner said, the week of front-page headlines about Iraq could do political harm to Blair, who has been the Bush administration's most staunch ally in the Iraq campaign. Blair's Labor Party is holding its annual conference next week, and aides said the prime minister had planned to emphasize his domestic agenda, including proposals for radical reforms of Britain's public services in health, education and transportation.

Instead, Kellner said, the focus would shift back to an increasingly unpopular war. "Every time Iraq dominates the news, it reminds people of the argument over why we went to war and that a lot of people have lost trust in Tony Blair," he said.

Speaking from the family home in Liverpool, Lil Bigley broke down in tears as she made a televised plea for her son's abductors to "show mercy to Ken and send him home to me alive." Propped up by two of her sons, she said that "he is only a working man who wants to support his family."

After her appearance, the family reported, she collapsed and was taken to a local hospital.

Earlier in the day, Paul Bigley accused the United States of intervening to prevent a prisoner release to which Iraqi officials had agreed. "We had a stay of execution and we have saved my brother's life for at least 24 hours," he told BBC radio. "That was a shadow of light in a big, long, dark, damp, filthy, cold tunnel. Now this has been sabotaged."

He added: "Is this a puppet government, or are the Americans moving the goal posts to suit their own aims again?"

But Blair received unsolicited support from his main political opponent, Michael Howard, leader of the Conservative Party. Howard said he hoped the Bigley family would forgive him for wholeheartedly endorsing Blair's stance.

"We cannot give in to people who behave in this barbaric fashion," Howard told the BBC. "It would be a green light to them to take more hostages and kill more people. I feel desperately for Kenneth Bigley and his family. And I feel for Mr. Blair, too, who is in the most unenviable predicament."

Flanked by two of her sons, Lil Bigley, mother of Kenneth Bigley, appeals to his kidnappers to "show mercy to Ken and send him home to me alive."