Whatever the world thinks of Robert Novak, Robert Novak wants the world to know that he doesn't much care. "I don't watch my words very closely. I'm 76 years old, and I don't have that much time on this earth," says the conservative columnist, his hand tapping idly on a chair in his downtown Washington office. "There's very little people can do to hurt me, and so I say what I want to say."

And so he does. Four years ago, that was what made Novak the most notorious journalist in Washington. On July 14, 2003 he wrote a column - which is syndicated in almost 300 papers nationally, including the Washington Post - that contained the name of CIA operative Valerie Plame. The piece led to a three-year investigation into how her name was leaked, a 30-month jail sentence for vice presidential aide Lewis "Scooter" Libby, and the biggest personnel scandal of the Bush administration.

Two weeks ago, that scandal appeared to be on the verge of running its course. President Bush commuted Libby's sentence, and Plame's damage suit against Dick Cheney was thrown out of court. But now Novak has wandered back into the fray with a new memoir, titled, after his old nickname, The Prince of Darkness.

It is a title that the book tries its best to live up to: settling scores across five decades, discussing his best sources and favourite scoops, and reigniting the debate over whether or not he should have included the name of Plame.

The role of the sinister Washington insider is one Novak has cultivated with cartoonish consistency. He has worked out of the same address, a handsome building one block from the White House, for 43 years. He wears a three-piece pinstripe suit every day, his braces now stretched by weight and age. As he holds forth on the failures of what seems like every politician he has ever known, his jowls and arched dark eyebrows form into a familiar scowl. Around his neck is the same stained orange and blue tie that he is wearing on the cover of his new book.

Fifty years in Washington have not made Novak an optimistic man. "I don't have a lot of faith in the political process or politicians," he says. "They're all disappointing, because they're just politicians. The only perfect man was Jesus Christ, and he's never run for anything that I know of." Despite being often accused of using his column to serve the interests of powerful Republicans, his verdict on the current president is succinct: "George Bush is one of the worst presidents I have ever seen."

Novak came to Washington in 1957 as a reporter for the Associated Press and joined Wall Street Journal in 1958, where he covered the Senate and solidified his reputation as an able political reporter. In 1963 he accepted an offer to write a nationally syndicated column from New York with Herald-Tribune reporter Rowland Evans, a partnership that produced one of the great institutions of Washington journalism. The career has given Novak a bottomless supply of stories to draw on - from meeting Ezra Pound in the Senate, to a reckless midnight car ride with John F Kennedy, to having his wedding reception hosted by Lyndon Johnson.

Evans retired in 1993 and died in 2001, but Novak continues to write the syndicated column, now three times a week. And, unlike most of his fellow columnists, his work is still based mostly on gossipy inside reporting, not opinion. He is well known for using unnamed sources in high places. Of top presidential aide Karl Rove, he writes: "In 44 years as a Washington reporter, I never had better access to a White House as I did to the George W. Bush administration. Karl Rove was a grade A-plus source."

His sourcing methods and lack of firm ideological commitments open Novak to criticism from the right and left. In 2003, former Bush speechwriter David Frum wrote a cover story for the conservative National Review magazine that charged Novak with being unpatriotic in the fight against terror, and last week he published a three-part critique of Novak's new memoir on the magazine's website. "One of the things I found so shocking about Novak's memoir was his use of his very powerful column for personal ends," Frum says. "Lots of Washington insiders exchange better treatment for information, but Novak is one of the few who uses that to exact retribution."

Critics say that this habit was on display nowhere better than during the Plame affair. Geneva Overholser, a professor of journalism at the University of Missouri who has criticised Novak in the past, says he represents "the worst in insider Washington journalism". "It seems to me that for Novak access is the most important thing - and he surely does have it. But his behaviour shows just how much harm you can do as a journalist when access is everything. He allowed a powerful person to make a damaging assertion about someone else under the cover of anonymity."

Of course, Novak has harsh words for his critics, too. He describes Frum as "a dishonest journalist and a fraud", and writes in his memoir that Frum's attacks were motivated by personal animus. He is equally dismissive of Overholser: "Journalists of Overholser's stripe despised me for being a conservative," he writes.

But the most damning judgments are reserved for Plame's husband, Joe Wilson, of whom Novak writes: "What an asshole!" He remains unrepentant. "That wasn't a conclusion I reached after three years," laughs Novak. "That was a conclusion I reached after three minutes."

Novak does seem to have some remorse about the fallout from his column, and says he regrets "all the trouble that happened". But he sees little in his own conduct to apologise for. "It's an irrelevant question to ask what I would do if I could do it all over again, because I don't have the chance to do it all over again. It's done."

Novak argues that revealing Plame's identity did not endanger her in any way. Wilson disagrees. "We have received any number of death threats since her name came out from al-Qaeda types or al-Qaeda wannabes." He plans to push ahead with his damage suit against Cheney, Libby, Rove and others in the Bush administration for revealing his wife's identity as a CIA agent. Wilson says he filed a notice of appeal on July 20.

He is still bitter about Novak's actions. "I think it's very clear that he's got, at best, an occasional relationship with the truth. And as a Catholic he ought to remember that bearing false witness is a sin." Novak says that Catholic faith - to which he converted from Judaism in 1998 - helps him put the criticism in perspective. And, he says, despite three bouts of cancer and two broken hips, he has no plans to retire. "I'll keep writing the column as long as people print it. That might be an open invitation for people not to print it, but I hope not."

All he hopes is that there are no more questions about Plame. "You can't imagine how tired I am of answering those questions. But it's my fault for bringing it up - after all, I wrote this book."

Why naming Plame mattered

When President George Bush made the case for invading Iraq in January 2003, he alleged that Saddam Hussein had attempted to buy yellowcake uranium from Niger. On July 6 of that year a former US ambassador, Joseph Wilson, published an article in the New York Times that disputed the president's claim. Wilson wrote that the CIA had sent him to Niger in 2002 to investigate the yellowcake story, and he had found no evidence of an attempted sale.

A week after Wilson's article was published, Robert Novak wrote a column in which, on the basis of information provided by two anonymous "senior administration officials", he reported that Wilson had been sent to Niger only at the request of his wife, whom Novak identified as "CIA operative" Valerie Plame. Novak did so even though the CIA had asked him not to use Plame's name.

Because revealing the identity of an undercover CIA agent can, in certain circumstances, be a criminal offence, a special prosecutor was appointed in February 2004 to investigate the "alleged unauthorised disclosure" of Plame's name.

Dozens of journalists and administration officials - including the president - were interviewed, and vice presidential aide Lewis "Scooter" Libby was convicted of criminally obstructing the investigation. Novak's sources were revealed to be the then deputy secretary of state Richard Armitage and top presidential aide Karl Rove. Novak, Rove and Armitage were never charged with any offence.