LONDON — Former Prime Minister Tony Blair faces harsh questioning Friday on the 2003 decision to invade Iraq — the fateful decision blamed by many for cutting short his political career.

Blair's testimony is expected to provide the highlight of the Iraq Inquiry, a wide-ranging investigation of the behind-the-scenes machinations that brought Britain into a costly and unpopular war. The audience will include family members of soldiers and civilians killed or missing in Iraq.

Blair is expected to be questioned about charges that he and his inner circle were so determined to topple Iraqi dictator Saddam Hussein that they exaggerated intelligence reports about Iraqi weapons systems and pressured Britain's attorney general to issue a ruling that the invasion would not be a violation of international law.

The leader characterized by satirists and columnists as "Bush's poodle" will also be questioned about whether he gave President George W. Bush an early, firm assurance that British troops would join U.S. forces in the invasion without consulting Parliament or the public.

"The three key issues are whether Blair's agreement to military action was intended to achieve regime change, whether the intelligence on Iraqi weapons was as conclusive as he claimed, and the legality of the war," said journalist Chris Ames, whose Iraq Inquiry Digest Web site has chronicled the hearings that began in November.

He said it became clear this week when former Attorney General Peter Goldsmith testified that the top legal adviser only changed his position and decided the war was legal after meeting with lawyers in ex-President George W. Bush administration in Washington.

Blair's government has been criticized for publishing a dossier asserting that Saddam Hussein posed an imminent threat because of his chemical and biological weapons capability, including missiles that could be launched within 45 minutes. Those claims proved false.

Earlier testimony has revealed that a parade of government lawyers and top British diplomats agreed the war would be illegal without a United Nations security council resolution specifically authorizing the use of force but were overruled by Blair.

Evidence presented to the Iraq Inquiry suggests that Blair made a personal commitment to Bush during a 2002 visit to the president's Texas ranch — long before he told the British public that an invasion was needed.

It was public unhappiness with the war — which deepened after no weapons of mass destruction were found — that gravely weakened Blair's hold on power, leading him to step down in 2007 after more than a decade in power.

"It changed the way I felt about him, and that's true of a lot of people in this country," said office worker Mina Kurunis, 23, of London. "It doesn't seem like there was enough evidence. It seemed like it happened really quickly without people really talking about it."

Bob Worcester, founder of the Ipsos MORI polling firm and author of a book about Blair's 1997 landslide, said the Iraq war marked a turning point in Blair's relationship with the once-adoring public.

"He was the Barack Obama of his day, enormously popular, but after the war there was deep public skepticism about him," said Worcester, citing polls showing Blair's plummeting approval ratings after the invasion.

The five-person Iraq Inquiry panel is expected to issue its report late next year but is not charged with assigning blame or determining if there was criminal conduct. (AP)