"Robert D. Novak, one of Washington's best-known and most controversial columnists for nearly half a century, has a brain tumor.

Novak, 77, said yesterday that the diagnosis was made Sunday and that he was admitted to Brigham and Women's Hospital in Boston, where he will soon begin treatment. "I will be suspending my journalistic work for an indefinite but, God willing, not too lengthy period," he said in a statement.

"He is talking," said an assistant, Amanda Carey. "Everyone's optimistic right now. He's in good spirits." Novak's office said no tests had yet determined whether the tumor was malignant. He became ill when he and his wife went to visit their daughter near Cape Cod, Mass.

Last week, while driving his black Corvette, Novak hit a homeless pedestrian at a downtown Washington intersection. He said he did not realize he had struck anyone until a passing bicyclist stopped him. The 86-year-old pedestrian suffered minor injuries, and Novak received a $50 ticket.

Novak has had cancer diagnosed at least three times, and in 2003 underwent surgery to remove a cancerous growth on his kidney.

The conservative commentator launched a column in 1963 with his longtime partner, the late Rowland Evans, and continued the column, which is carried by The Washington Post, after Evans retired in 1993. The column became more ideological as Novak began moving to the right later in the 1960s.

Although Novak is a pugnacious figure who revels in his "Prince of Darkness" nickname, friends and colleagues describe him differently. "He's a lot nicer than he ever comes across on the screen," said Jack Germond, a retired liberal columnist and frequent sparring partner.

"I came to really respect and admire the guy -- not easy," said MSNBC commentator Tucker Carlson. "He's the toughest human being I've ever met in my life. Nothing bothers him." Carlson recalled seeing Novak deck a protester who had called him a traitor and shoved him in New Hampshire four years ago. "He just kept walking and didn't look back," Carlson said.

Novak was a CNN commentator for 25 years, co-hosting the program "Crossfire" and serving as a panelist on "Capital Gang." He left the network three years ago after uttering a curse word and walking off the set. He is now an analyst for Fox News.

Novak became a lightning rod for criticism in 2003 when he identified Valerie Plame, the wife of administration critic Joseph C. Wilson IV, as a covert CIA operative. Novak obtained the information from Richard L. Armitage, then a State Department official, and confirmed it with Karl Rove, then a senior White House aide to President Bush, without identifying them. The column triggered a lengthy investigation that led to the perjury and obstruction-of-justice convictions of Vice President Cheney's former top aide, I. Lewis "Scooter" Libby, whose sentence was commuted by the president.

Novak's most vociferous critics accused him of treason, and he received a steady flow of hate mail and threats. "What was frustrating was that there were a lot of crazy things being said, that I had taken the Fifth Amendment or that I had made a plea bargain. . . . It's obviously caused me a lot of trouble," he said in a 2006 interview. "If I had it to do all over again, would I have done it? It's a hard question to answer."

Brit Hume, Washington managing editor for Fox News, said Novak has never lost his enthusiasm for reporting. "He has very distinct and well-known political preferences -- he's a strong conservative -- but an absolutely cold-blooded and dispassionate analyst of the state of political races," Hume said. "He's a reporter to his core."

For example, Novak wrote in yesterday's column that "John McCain seems wooden, with a campaign that appears to be in shambles."

Steve Huntley, a Chicago Sun-Times columnist who worked closely with Novak when he was editorial page editor, said Novak never took vacations and never missed a deadline, even after breaking his hip and suffering "some illnesses people didn't know about. . . . He's never been one to shy away from controversy. That's made him a target for some people on the left who disagree with Bob's conservative principles."

A former reporter for the Associated Press and Wall Street Journal, Novak has written about battling a drinking problem, and a $1,000-a-day gambling habit, until suffering a near-fatal case of spinal meningitis.

He often forges a close relationship with those who leak information. In his autobiography, published last year, Novak described how he and Rove, "a grade A-plus source," dined at each other's homes at the start of the Bush administration. He said he did not criticize Rove until, and then only mildly, the Bush aide cut him off in 2003, because reporters "do not attack their sources."

Novak has served as a conduit for Republicans for decades. He reported last week that McCain was expected to announce his running mate within days but later concluded that he had been used to float a phony rumor. In his memoir, Novak said much the same about his publication of a questionable leak from the Nixon White House.

"We were so ravenous for exclusive news that we were susceptible to manipulations by leaks, compromising our credibility," he wrote.

In an interview last summer with London's Guardian, Novak said: "I'm 76 years old, and I don't have that much time on this earth. There's very little people can do to hurt me, and so I say what I want to say."" (Howard Kurtz, The Washington Post, July 29, 2008)