Dan Rather stands waiting to be recognized, calm amid the cries of "Mr. President," and cool in the press conference glare. President Nixon half smiles and seems to tense as he points to Rather. It is the beginning of another confrontation in what has become a running, real-life drama in prime time television.

The most recent encounter came during the President's press conference in Houston. When CBS White House correspondent Rather introduced himself, the nonworking press in attendance applauded and Mr. Nixon asked, not good-naturedly, "Are you running for something?" Rather, usually unflappable, was a mite rattled this time and shot back rudely, "No sir, Mr. President, are you?" Then he asked a tough Watergate question.

The brief dialogue dripped bitterness, like an exchange of kidney punches between two boxers who, having fought often and inconclusively, have come to dislike each other personally. And there were practically audible gasps at the breach of press conference decorum. To Rather, a 42-year-old tall, dark, handsome and persistent Texan, his role is to be neither "an attack dog or a lap dog. I want to be a watchdog. If I see something wrong, I start barking and barking and barking. Sometimes I'm wrong; sometimes I'm not."

He has been barking at presidents since 1964, when he won the White House beat by his reporting of the Kennedy assassination from Dallas when he was CBS Southern correspondent. Lyndon Johnson called him "Dan," but treated him as something of an apostate. How could Rather, a fellow Texan, be pressing all those prickly questions?

As for the present incumbent, Rather insists, "I feel no hostility toward Mr. Nixon. He was pleasant when I dealt with him in '66 and '67. But I knew from the day he became President that we weren't going to get along. He's a distant person. It's his nature that he needs to be by himself, and in his job that can't be."

President Nixon and his staff have made no secret of their dislike of Rather for what they consider to be his unnecessarily critical treatment of the President. In 1971 presidential aide John Ehrlichman made a special visit to CBS News president Richard Salant to complain about Rather and suggest that CBS might transfer Dan to, say, El Paso.

Rather lives in the affluent Georgetown section of Washington but does not get home all that much, between tailing the President and shuttling to New York once a week to anchor the Saturday CBS Evening News. There is little time left to spend with his wife Jean and their children, a daughter, Robin, 15, and Dan Jr., 13, much less any leisure for his old escapes of hunting, fishing and tennis.

Though he has never broken any Washington story of any more significance than the dismissal of draft director Lewis Hershey, Rather's dogged aggressiveness often makes his colleagues in the White House press corps seem pallid by comparison. Still, almost all speak highly of him. Rather's NBC counterpart at the White House, Tom Brokaw, says, "He's very good, goddammit."

The only substantive criticism Rather gets from journalism professionals is for his tendency toward impetuousness and running with a rumor. He mistakenly reported the "resignation" of J. Edgar Hoover, for instance. In any case, his zealousness and his one-upping competitiveness with CBS colleagues probably don't help him in the Walter Cronkite succession sweepstakes, the race among CBS News' second bananas to succeed the 57-year-old anchorman when he retires. The morning line puts Rather behind Roger Mudd by a substantial margin in the derby. Mudd already takes over as anchorman during Cronkite's long vacations. And Rather's on-air tangles with a President may not be conducive to a soothing, supper-news statesman image.

But Rather, for public consumption at least, says he is happy making presidents sweat. Mustering all of his drawling charm, Rather smiles pleasantly and explains, "I'm not trying to win a popularity contest."