But at home, and in much of mainland Europe, many people will see him differently.
But Blair, through conviction and political calculation, has steadfastly backed the United States, which he promised to do within hours of the terrorist attacks on the Pentagon and World Trade Center.
Neither Germany's refusal to get involved in a war nor France's strong reluctance has led to signs that Blair will deviate from a course that looks increasingly as if it will lead to war. Neither have public opinion polls in Britain, which show that more than 80 percent of respondents oppose an invasion of Iraq. If anything, as Germany and France have restated or increased their opposition to war, Blair has become an even more important player on the world stage by sticking with the United States.
He has been both a vocal backer of military force, if necessary, and a private voice of caution, having urged Bush to seek a United Nations resolution before using force, a counter to arguments from Vice President Dick Cheney and Secretary of Defense Donald H. Rumsfeld.
"Blair has positioned himself, has won the credibility, to become a player in the Bush administration," said Michael Clarke, director of the International Policy Institute in London. "Bush listens to Rumsfeld, Cheney - and Blair."
The prime minister's public comments indicate that he has strong sway over Bush. In arguing for Hussein's removal, Blair was using the term "disarmament" at every opportunity - a term more palatable among European leaders than "regime change," which the Bush administration had been using for months before reshaping its arguments using Blair's vocabulary. Before the bombing of Afghanistan, it was Blair who urged - and had a strong hand in arranging - an international coalition to take part.
He is now pushing for a second U.N. resolution as debate within the Bush administration apparently continues.
"I think history will judge him very well in regard to him being a tempering force," said Clarke. "His problem isn't history but the current risks at home."
Indeed, Blair, while working to rally world support for a possible attack against Iraq, has had little success in Britain. With the exception of a few brief periods - the Suez Canal crisis of 1956 is one example - the United States and Britain have been staunch allies, a relationship cemented by World War II. That has worked well for the United States for reasons of diplomacy, and it has helped maintain a world role for Britain.
The alliance also gives Britain definition. The French can usually be counted on to try to be a broker in world affairs and then follow the U.S. lead. The Germans are reluctant, for historical reasons, to become involved in any war and can be counted on, as the largest economy in Europe, to push multilateral solutions with Europe playing an important part.
"For us, it's being allied with a superpower, having influence over a superpower that we wouldn't have if we weren't such close allies," said Douglas Hurd, British foreign secretary during the Persian Gulf war in 1991. "I don't think it's wise to put too much weight on sentiment, this 'shared culture' and 'shared language' and this sort of thing.
"It really boils down to what different prime ministers have seen to be in our national interest, and what Tony Blair sees as our self-interest is abundantly clear. That carries risks here at home."
In fact, Blair's stance has been opposed not only by the public at large but by many people within his own left-leaning Labor Party, including ministers within his Cabinet. His biggest supporters have been from the opposition Conservative Party.
In Britain's Parliament on Wednesday, Blair spent much of the time devoted to Prime Minister's Questions, in which he is routinely criticized and taken to task by Conservatives, being heckled and questioned by members of his own party.
Labor's back-benchers yelled, "Who's next?"
Calm, as always, Blair responded: "After we deal with Iraq we do, yes, through the United Nations, have to confront North Korea about its weapons program."
"When do we stop?" yelled one Labor member.