In my first year in America, as a budding young conservative, my old friend, the writer John O’Sullivan, invited me out to dinner. The dinner, it turned out, was with none other than William F Buckley, a man who remains the undisputed titan of American conservatism.

Buckley became famous in America in the 1950s and 1960s for being a conservative intellectual when such a thing was regarded as axiomatically oxymoronic. He founded the National Review, the indispensable magazine for the burgeoning American conservative movement.

He was one of the inspirations for Barry Goldwater’s emergence as a conservative Republican nominee in 1964, and instrumental in Ronald Reagan’s long, steady intellectual march to power. I wasn’t having dinner with just anyone that night — but with a man for whom the phrase eminence grise seemed to have been invented.

I recall this because if Buckley has decided George W Bush is not a conservative, it cannot be easily dismissed. Some of us were so appalled by Bush’s profligate spending, abuse of power and recklessness in warfare that we reluctantly backed John Kerry in 2004 as the more authentically conservative candidate. Many Republicans scoffed. Now fewer do.

“I think Mr Bush faces a singular problem, best defined, I think, as the absence of effective conservative ideology,” Buckley recently explained. “[The president] ended up being very extravagant in domestic spending, extremely tolerant of excesses by Congress. And in respect of foreign policy, incapable of bringing together such forces as apparently were necessary to conclude the Iraq challenge . . . There will be no legacy for Mr Bush. I don’t believe his successor would re-enunciate the words he used in his second inaugural address because they were too ambitious. So therefore I think his legacy is indecipherable.”

His legacy, I’d argue, is actually quite decipherable. It includes two bungled wars, a doubling of the national debt, a ruination of America’s moral high ground in the war against Islamist terror, the worst US intelligence fiasco since the Bay of Pigs, and the emergence of Iran as a regional and potentially nuclear power with control of the West’s energy supplies.

But the damage to America itself — to its cultural balance and constitutional order — is just as profound. In a recent CNN story on Southern women and the Republicans, one voter explained: “There are some people, and I’m one of them, that believe George Bush was placed where he is by the Lord. I don’t care how he governs, I will support him. I’m a Republican through and through.”

American conservatism has gone from being a political philosophy rooted in scepticism of power, empirical judgment and limited government into an ideology based in born-again religious faith, immune to empirical reality and dedicated to the relentless expansion of presidential clout. It sanctions wiretapping without court warrants, indefinite detention without trial and the use of torture.

Last week saw perhaps the tipping point in the reawakening of the traditional conservative perspective. In the Senate, the president’s bid to legalise torture and ad hoc military tribunals was stopped not by the Democrats but by four key Republican senators: John McCain of Arizona, the frontrunner for the Republican nomination in 2008, John Warner of Virginia, Lindsey Graham of South Carolina and Susan Collins of Maine.

They were supported by the former secretary of state, Colin Powell, who penned a public letter to McCain opposing Bush’s detention policies. “The world is beginning to doubt the moral basis of our fight against terrorism,” Powell observed. “To redefine common article 3 [of the Geneva convention] would add to those doubts. Furthermore, it would put our own troops at risk.”

It is hard to dismiss McCain and Powell as men who do not know a thing about war or torture. One was tortured by the Vietcong; another actually won a war in Iraq. The contrast with the current White House is almost painful to observe.

Two weeks ago, word leaked that the president’s political guru, Karl Rove, was hoping to use the issue of who was tough enough on military prisoners against the Democrats in the November congressional elections. He was going to tar them as wimps again for not waterboarding terror suspects. But that strategy was stopped in its tracks by Senator Graham.

“This is not about November 2006. It is not about your election,” Graham declared with passion. “It is about those who take risks to defend America.”

Graham is also a former military lawyer and, along with the entire legal leadership in the US military, opposes Bush’s military kangaroo courts. “It would be unacceptable legally in my opinion to give someone the death penalty in a trial where they never heard the evidence against them,” he said of the White House proposal. “‘Trust us, you’re guilty, we’re going to execute you, but we can’t tell you why’? That’s not going to pass muster; that’s not necessary.” It’s also, well, not American.

To add to the revolt, last week six leading conservative writers penned separate essays on why the Republicans deserve to lose the November congressional elections. Here’s a stunning quote from one of them: “The United States has seen political swings and produced its share of extremists, but its political character, whether liberals or conservatives have been in charge, has always remained fundamentally Burkean. The constitution itself is a Burkean document, one that slows down decisions to allow for ‘deliberate sense’ and checks and balances.

“President Bush has nearly upended that tradition, abandoning traditional realism in favour of a warped and incoherent brand of idealism. At this dangerous point in history, we must depend on the decisions of an astonishingly feckless chief executive: an empty vessel filled with equal parts Rove and Rousseau.”

That passage was written by Jeffrey Hart, a speechwriter for Nixon and Reagan and another pillar of the conservative movement. It’s a sign of a brewing conservative revolt against Bush’s policies that may crest at November’s elections.

Bush has allies in the House of Representatives — but what appears to be a unified and stalwart resistance in the Republican-controlled Senate. It turns out that the US does have a functioning opposition party after all. It’s called the authentically conservative wing of the Republicans.

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