Given such a purple introduction, Gitlin, a professor of journalism and sociology at Columbia University, cuts a rather conservative figure in the lobby of Manhattan's Grand Hyatt. Bearded and dressed professorially in V-neck sweater and denims, Gitlin is the archetypal liberalthinking commentator and has just written The Intellectuals And The Flag, which he hopes will ?contribute to a new start for intellectual life on the left". The time has come for left-leaning academics to engage with ordinary Americans and eschew ?kneejerk negativism, intellectual fads and political orthodoxy".

In particular, Gitlin, who has been described as ?a latter-day Tom Paine", argues that the left should make clear that they are first and foremost patriots and that what's needed is tough-minded criticism and a desire to examine anew the global role of the US post-9/11. It's not enough, he insists, merely to bash the Bush administration. If the left . . . by which he means the Democrats . . . is to displace the Republican right in power it must give the American people an alternative vision, not only of their own country but of the world.

Intellectuals of the left, " Gitlin writes, ?need to do more than dissent . . . or praise.

We need to see the world steadily and see it whole: to see it without blinkers, to explain how things came to be as they are, to sharpen values and make them explicit, to sketch visions, to connect with publics in such a way as to suggest where our limping democracy might go."

At the moment, though, American democracy is not so much limping as crippled, principally by the likes of Horowitz, whose targeting of teachers has been compared to McCarthyism. He's been ?ranting and raving" for more than 20 years, says Gitlin. ?Mostly I just ignore him. My initial inclination when the list came out was to ignore him again. But one of the appalling facts of our current environment is there are people who take him seriously, including state legislators, so I have to rebut his facts . . .his factual claims. You can't just let it go."

But how easy is Horowitz to rebut? His facts may be disprovable but isn't perception all?

Horowitz, " acknowledges Gitlin, ?is a very good propagandist. He knows that.

Charge someone with being anti-American and . . . as Karl Rove [Bush's chief strategist] said . . . or is said to have said . . . 'when you're explaining, you're losing'. You know: 'I haven't beaten my wife, ' says John Kerry."

Mention of Kerry brings back painful memories of Bush's second win in 2004.

Midway through his valedictory term, with the war in Iraq claiming more victims daily and the president's popularity rating at its lowest ebb, the mood on the American left has never been bleaker. Irrespective of the situation in the Middle East, or what Americans think of their leader, there is no possibility, other than impeachment or assassination, of removing him.

It is, says Gitlin, a flaw in the American system, especially now, as the Bush administration dominates both houses of Congress. Any opposition is muted and four years must pass before there is even a possibility of change. ?Effectively, you have only one moment of sovereignty every four years, " he sighs. ?You have elections. And then you have a four-year dictatorship. This is not good. I mean it's only a potential, normally, that it be not good in this way but Bush obviously believes in pushing his scope of power to the maxim so there's no check or balance whatsoever."

What, then, can the Democrats do? A top priority, says Gitlin gloomily, is to discover a credible candidate who can make a push for the presidency. That, though, is easier said than done. He can think of no ?vivid, national figures, no defining personality. It's a failure of a whole political generation to generate a confluence of interests, character and oratory. There is nobody who has the right personal story to look like the standardbearer. Rhetoric is threadbare."

Recently, he gave a talk in Reno, Nevada, where he asked politically knowledgeable people about Harry Reid, the state's senior senator and one of the few ?visible" national Democrats. The vibe was not encouraging.

The best that could be said was that he is a nice guy. On the debit side, he lacks leadership skills and has never uttered a memorable phrase in his life.

This is not the stuff of which Roosevelts are made. But nor do other prominent Democrats set the prairie on fire. When Al Gore is being touted for a comeback, the omens for 2008, when septuagenarian John McCain is expected to be the Republicans' candidate, are dire.

I think we're living in a state of emergency, " says Gitlin. ?An opposition leader could catapult himself to prominence if he had the both the platform and the capacity to use it. Getting the platform is hard. But if you were really good, if you were really professional, you could do it. You could become the guy that all the Sunday shows go to, you could become the automatic standard-bearer. You could become the idol of attention."

But the dilemma may be even more deeprooted than that. While the Republicans, like the Tories, appear to believe they have a god-given right to govern, the Democrats' attitude towards power is at best ambivalent. ?Power, " says Gitlin, ?makes them nervous. They're squeamish about it.

They don't like hierarchies. They don't like the schmoozing, they don't like the bargaining, they don't like the backrooms."

Added to which is the difficulty of knowing exactly what Democrats stand for, which is not a problem their opponents have.

For good or ill the Republicans are associated with enterprise, individualism, go-getting. In short, the perception is that they are optimists to whom everything is a challenge. In contrast, the Democrats are seen as pessimists beset by problems, which is certainly true at the moment. In the popular imagination, the former seem to embody the true spirit of America.

In The Intellectuals And The Flag, Gitlin attempts to redress the balance, insisting that being a Democrat makes you no less an American. Like Orwell, he loves his country but reserves the right to dislike its government. It was from that standpoint he protested against the Vietnam war. He supported the use of force against al-Qaeda and the Taliban in Afghanistan, but was against attacking Iraq.

A few days after 9/11, inspired by the passengers on one of the planes who sacrificed their lives, he and his wife hung up the Stars and Stripes. ?It was not meant as support for the policies of George W Bush, " he writes, ?but as an affirmation of fellowship with an injured and resolute people." Some weeks later, they took the flag down. Already, ?the lived patriotism of mutual aid was in retreat around us and the symbolic substitute felt stale". Bush's bellicose posturing was bad enough. But equally hard to stomach was the Democrats' abject deference. Without opposition, without dissent, politics cease and democracy dies. As the US foisted democracy on Iraq, its own fragile version was withering on the vine.