The catastrophe in New Orleans, which has aroused deep sympathy here, is so overwhelming that day-today politics on the other side of the Atlantic must seem more than usually remote. The Conservative Party has been out of office for more than eight years and is not likely to regain power in Britain for at least four more. So the question of who leads it may seem academic just now.

Yet the launch this week of Kenneth Clarke’s campaign to lead the party that has dominated British politics for most of the last century does matter – if only because it demonstrates why Prime Minister Blair has been right to support American policy in Iraq.

Mr. Clarke is the last “big beast” of the Thatcher era. Between 1979 and 1997, he did most of the major jobs in government, finishing up in charge of the Treasury for five years and establishing a postwar record for continuity in office. As chancellor of the exchequer, Mr. Clarke raised taxes but restored economic stability. His bluff, saloon-bar manner still impresses the kind of voters who say they don’t like politicians.

Though Mr. Clarke is 65 and would therefore be nearly 70 by the time of the next general election, he has an appeal to an aging electorate. The record of septuagenarian prime ministers is not a bad one: they include Churchill, Gladstone, Disraeli, and Palmerston. Americans, who are used to senior politicians such as Secretary of Defense Rumsfeld and President Reagan, might be puzzled by the emphasis on the age issue.

There are several reasons why Mr. Clarke might be lucky in his third bid for the Tory leadership. First, the competition is not especially formidable this time. The favorite, David Davis, is not particularly popular – either with the voters or with his parliamentary colleagues. His main rival, David Cameron, is young and almost unknown outside Westminster. Neither can compete with Mr. Clarke’s political experience.

The second reason why Mr. Clarke has thrown his hat in the ring has to do with Europe. He belongs to a generation of Conservatives, led by the late Edward Heath, for whom the project of European Union was akin to a religion. They were (and are) positively enthusiastic about big government, and the idea of a European superstate promised an alternative to the apparently inevitable decline of British power and prestige.

Margaret Thatcher changed all that. Her change of heart on Europe, turning against the submission of British interests to an increasingly meddlesome Brussels bureaucracy, split the Tory party, leaving Mr. Clarke in a stubborn but dwindling minority. When he stood for the leadership in 1997 and 2001, he lost both times, largely because his pro-European views were out of step with his party and, increasingly, the country.

Now, in his mid-60s, Mr. Clarke has apparently been mugged by reality. Though he campaigned for a single European currency, and would still prefer to have abolished the pound sterling, he accepts that the success of the British economy outside the eurozone has killed the issue for the foreseeable future. The French and Dutch referendums have similarly dashed his hopes of a European constitution any time soon. So Mr. Clarke hopes that the Conservative Party will now ignore his lifelong record of devotion to the European cause, and give him the job that, but for Europe, would have been his eight years ago.

The third and most interesting reason why Mr. Clarke is making a pitch for the Tory leadership now has to do with America and Iraq. Like his friends in Paris and Berlin, he opposed the war and hardly bothers to conceal his contempt for the Bush administration. His emergence at this juncture is not accidental. When Mr. Blair made the decision to support President Bush, it was of crucial importance that he was staunchly supported by the then Conservative leader, Iain Duncan Smith. Without that support, it is unlikely that Mr. Blair would have risked such a huge political gamble and certain that he could not have retained his majority in the House of Commons when it came to vote on the war in 2003. He would have been forced to resign, Mr. Bush would have fought alone, and last year’s American election might have gone the other way.

But Mr. Duncan Smith was blamed by many Tories for playing the part of Her Majesty’s loyal opposition. He lost his job later that year, to be replaced by Michael Howard, whose attitude to Iraq and Mr. Bush was much more ambivalent. While claiming to support the war, Mr. Howard seized every opportunity to undermine Mr.Blair’s conduct of it. Tory opposition to the war has grown steadily, fueled by the anti-Americanism that led the White House to declare Mr. Howard was no longer welcome. But in last May’s election, Mr. Blair trounced Mr. Howard partly because he was able to depict this unprincipled attitude to the war as unpatriotic.

Now Mr. Clarke, who is not ambivalent about the war but consistently hostile to it, is attempting to exploit its present unpopularity. He declares that now is not the time to crow, “I told you so,” though, evidently, that is exactly what he intends to do.

In the next few weeks, the Conservatives will have to make up their minds. If they elect Mr. Clarke, they will find themselves in the role once played by the Labor Party: anti-war, anti-American, and – in the eyes of many voters – anti-British. Mr. Blair, whose leadership has been galvanized by the terrorist attacks on London, must feel very comfortable at that prospect.