Treachery is bad enough at any time, but treachery in time of war is unforgivable. This week the atmosphere at Westminster has been sulphurous, as plot after plot against the prime minister has surfaced. As I write, the outcome is still unclear. The attempt by a large section of the parliamentary Labor Party to force Tony Blair to leave Downing Street less than 18 months into his third term of office may yet succeed. If it does, his premature departure will mark a defeat for the Western coalition in the war on terror — and a victory for the appeasers.

After nine years in office, any leader inevitably accumulates enemies, and Mr. Blair is no exception. His record is uneven. In domestic policy, the best that can be said for Mr. Blair is that, while previous Labor administrations were brief interludes that invariably ended in tears, he has forced the Conservatives to dance to his tune. If he is forced out of office, however, his goal of permanently shifting the Labor Party to the Right may yet prove unattainable.

It is in foreign policy, however, that he has been outstanding. As a war leader, he has been both resolute and astute. Like Winston Churchill in the Second World War and Margaret Thatcher in the Cold War, Mr. Blair grasped the crucial importance of the Atlantic alliance in the war on terror. By gaining the confidence not only of President Bush but of the American people, he made it possible for Britain to make a unique contribution to the defense of Western civilization.

Mr. Blair has paid a heavy political price for his loyalty to Mr. Bush, but he has done so willingly because he recognized already during the Kosovo conflict in 1998 that Britain’s values and interests are closer to those of America than they are to those of continental Europe. The same cannot be said for most of his Labor colleagues, the strength of whose anti-Americanism is matched only by the weakness of their patriotism.

The fact that Mr. Blair is nominally a politician of the centre-Left was initially a source of strength for him as a war leader. It enabled him to build a national consensus in favor of a global war against Islamist terror which might have eluded a more divisive figure such as Churchill or Thatcher, both of whom came to office when Britain was already engaged in the struggle against Nazism and Communism.

It would be a mistake to suppose that Mr. Blair faced an easy task in winning public approval for the American rather than the European approach to the Islamist threat. Support for the counter-terrorist war in Afghanistan and Iraq has proved harder to sustain on both sides of the Atlantic than more conventional wars of the past. Low-intensity conflict requires high-intensity politics.

As time went on, however, the fact that Mr. Blair’s power base is on the Left has become a liability. The crunch came this summer with the war in Lebanon. If there is one issue that divides Mr. Blair from his party even more clearly than attitudes towards America, it is their attitudes to Israel. Not only is the hard Left increasingly aligned with the Islamists, even middle-of-the-road liberals are inclined to question the very existence of Israel.

As an illustration of this, consider the latest upsurge in anti-Semitic incidents in Britain since the outbreak of hostilities between Israel and Hezbollah. These attacks are now running at unprecedented levels, but the culprits do not fit the old stereotype of neo-Nazi skinheads. Many, predictably, are Muslim extremists, but there is a growing element of what might be termed illiberal liberals. These are usually white, middle-class, university-educated men and women. They blame Israel for Islamic terrorism and they blame Mr. Blair for supporting Israel’s right to self-defense. Usually they confine their views to dinner party conversation, but theory may ultimately translate into practice.

If Mr. Blair is brought down, it may be because his foreign policy — based on solidarity with America and Israel — has been successfully sabotaged. During his visit to America in July, at the height of the war in Lebanon, Mr. Blair received a memo from his Washington Ambassador, Sir David Manning, which claimed that his policy of refusing to call for an immediate ceasefire was disastrous for Britain’s image abroad. It was this act of disloyalty by his most trusted career diplomat that prompted Mr. Blair’s “wobble” in Los Angeles, when he suddenly seemed to give ground to the President’s critics — and his own.

Without the freedom to prosecute the war on terror, at home and abroad, as he believes right, the prime minister may feel there is no point in clinging to office. Already hampered by the sheer inertia of the British establishment, he has watched with visible frustration as the threat of home-grown Islamist terrorism has mushroomed. This radicalization of British Muslims is undermining American confidence in the country that has been the closest ally of the American-led coalition. Columnists like Mark Steyn are already asking, “Who lost Britain?”

Such are the restrictions imposed on European public discourse by multicultural correctness that these issues cannot even be discussed frankly. Mr. Blair, unlike Mr. Bush, dare not use a term such as “Islamofascism” that has been common currency in the transatlantic debate for years. The uncompromising speeches in which the prime minister outlined his war strategy a few months ago were barely reported back home. If neither his officials, nor his political allies, nor the media are listening, how can he expect the public to hear? His message about the existential threat posed by Islamist ideology has been drowned by the din of speculation about his future.

It is partly his own fault. He has never resolved the question of the succession. The speculation had already reached fever pitch two years ago, when uncertainty created by a minor heart operation prompted him to make two contradictory promises: that, if re-elected, he would serve a full third term and that he would not fight a fourth general election as prime minister. He was indeed re-elected, but these incompatible pledges have dogged him ever since.

Last month he refused to set a date for his departure, which his supporters would like to postpone until 2008. This week the threat of a revolt by more than a hundred members of Parliament forced his officials to let it be known that he would be gone within a year. When friendly newspapers suggested May next year as the date when he would announce his departure, to leave office in July, Downing Street issued no denial. Scenting blood, his enemies are demanding that he go much sooner, or even immediately.

The spectacle of Tony Blair at bay is not an edifying one. He has done the state some service, and he deserves better than to be defenestrated by political pygmies. My hunch is that he could rally public support even now, but I wonder whether he still has what it takes to turn the tables on the traitors.