NEW YORK (AP) - Dan Rather, whose nearly 24-year tenure as anchor of the "CBS Evening News" was clouded by a recent questionable report on President Bush's National Guard service, said Tuesday he will step down in March.
Rather said his last broadcast as anchor would be March 9, the 24th anniversary of when he assumed the position from Walter Cronkite.
The 73-year-old newsman said he will continue to work for CBS, as a correspondent for both editions of "60 Minutes."
"I have always been and remain a 'hard news' investigative reporter at heart," he said in a statement. "I now look forward to pouring my heart into that kind of reporting full time."
He made no mention of the National Guard story in announcing the change, saying he had agreed with CBS executives last summer to leave sometime after the Nov. 2 election. But he was forced to fight for his professional life after anchoring a September "60 Minutes Wednesday" story about Bush's service that turned out to be based on allegedly forged documents.
A report on what went wrong with the National Guard story, from a two-man independent investigative panel, is due imminently.
CBS didn't talk about potential successors. Newsmen John Roberts and Scott Pelley have long been considered in-house candidates, but the network will also probably look outside.
Rather has been with CBS News for more than four decades and made his name as a reporter covering the Nixon White House.
"He has been an eyewitness to the most important events for more than 40 years and played a crucial role in keeping the American public informed about those events and their larger significance," CBS Chairman Leslie Moonves said.
Rather's announcement comes eight days before his NBC rival, Tom Brokaw, steps down as "Nightly News" anchor and is replaced by Brian Williams.
The triumvirate of Rather, Brokaw and ABC's Peter Jennings has ruled network news for more than two decades. Rather dominated ratings after taking over for Cronkite during the 1980s, but he was eclipsed first by Jennings and then by Brokaw. His evening news broadcast generally runs a distant third in the ratings each week.
His hard news style was mixed with a folksy Texan style that led him to rattle off homespun phrases on Election Night. But odd incidents dogged him: In 1987 he walked off the set, leaving CBS with dead air, to protest a decision to let a tennis match delay the news. And his claim that he was accosted on the street by a strange man saying, "What's the frequency, Kenneth?" led rock band R.E.M. to write a song with the same name.
Brokaw said Monday that he was "pleased for Dan that he's come to a conclusion about his own life, as I have in my case."
"Dan and I have known each other competitively and personally for a long, long time," Brokaw said. "Occasionally on the competitive side, it would be tiny bumps in the road, but when you think of all that we've been through, we have a pretty strong relationship. So I wish him well."
ABC News said Jennings was traveling and could not immediately be reached for comment.
CBS thought it had an important scoop with the National Guard story this past September, reporting that President Bush had received preferential treatment to get into the guard and stay in the United States during the Vietnam War, and had failed to satisfy the requirements of his service.
But critics immediately questioned the story, saying a document purportedly written by Bush's late squadron leader appeared to be a fake. Rather apologized before CBS appointed the investigative panel.
"We made a mistake in judgment," Rather said, "and for that I am sorry."