At 9 o'clock this morning, or shortly thereafter, a small crowd will gather outside the office of CBS News President Van Gordon Sauter to wait for the weekly Nielsen ratings report on "The CBS Evening News With Dan Rather." Actually, it may be a larger crowd than usual. Last week could mark the 200th consecutive week that the Rather program has been No. 1 in the ratings.

Or a cold damp chill could run through CBS News headquarters in Manhattan if it turns out that "NBC Nightly News With Tom Brokaw," which the previous week nearly tied Rather's ratings, has managed to beat Rather and keep his winning streak at a mere 199 weeks, a humiliating blow to Rather and CBS no matter how much they would pretend it not to be.

"It wouldn't be all that grievous," Rather said yesterday from New York of the possibility that the ratings for last week could be in Brokaw's favor. "It would be our 200th consecutive week, yes, but I don't make very much of that. And I wouldn't make much of it if it didn't happen."

NBC's Brokaw, across town, was asked how he would feel if he were No. 1. "I'll be grateful for the moment, but I don't think of it as being anything more than that," Brokaw said. "One week or two weeks does not a trend make. What is most heartening to me is that the program is just doing better. It's just a stronger program every day."

This seismic jiggle in the network news ratings comes in the aftermath of an exceedingly news-intensive viewing month -- also a ratings "sweeps" month, when Nielsens count even more than usual. In February, the networks covered the follow-ups to the Challenger space shuttle disaster of late January, charted the nonviolent and very televisable overthrow of Ferdinand Marcos in the Philippines and sent their normally sedentary anchors packing to remote locations for extrastudio originations.

The month ended with the White House taking the unusual step of rebuking a network news organization (ABC, for letting Soviet mouthpiece Vladimir Posner rattle on after President Reagan's defense message) and with CBS cameras capturing for posterity the president's muttered opinion of reporters at a photo opportunity session who wanted to question him: "Sons of bitches," the president called them, reflecting the view his administration has held of the press from its beginning.

Ah, but they are hard-working SOBs, and they'll remember February as a demanding month, perhaps a barometric one in the way the three-network news ratings race went from a hearty simmer to an outright boil.

A CBS News spokesman said yesterday that according to overnight ratings recorded last week, "The CBS Evening News" will win its 200th consecutive week as planned, although the national Nielsens, which are received by the networks on teletype machines today, may be different. The previous week's blip in Brokaw's favor can be attributed to normal seasonal adjustments in the ratings, the spokesman said. As winter ends, CBS traditionally loses viewers.

Other CBS insiders, however, indicated there is a pervasive nervousness about the ratings. One source said a "general ratings malaise" throughout CBS, most noticeably in the prime-time entertainment ratings, was having an effect on the Rather program. In cities like Los Angeles and Chicago, once dominant CBS-owned stations are now foundering.

Timothy J. Russert, NBC News executive vice president, said that whether Brokaw won last week or not, the "Nightly News" is clearly coming from behind to be a newly formidable contender. "Our goal is to be Number 1 across the board," said Russert. " 'Nightly News' now is where the 'Today' show was a year and a half ago in terms of development."

"Today," which lagged behind ABC's "Good Morning America" for three years, recently overtook that program to become the No. 1 network morning news program.

"I think that from '79 to '84 there was a measurable drop in news viewing levels for all three networks," Russert said. "That was arrested in '84. Now in '84-85, 'Nightly News' went up 6 percent, ABC went up 2 percent, and CBS went up less than 1 percent. We have about three-quarters of a million new viewers out there."

Rather sounds statesmanlike and unworried. "To be the broadcast that every other broadcast is measured by is something to be proud of," he said. "I would rather be Number 3 and have the reputation of being a quality broadcast than be Number 1 and have the reputation of being crummy. The ideal of course is to be both -- best and first."

Sunday marks Rather's fifth anniversary as anchor of the "Evening News." He succeeded the seemingly unsucceedable Walter Cronkite in 1980. After some initial wobbling, he and the program became dominant, if not quite to the degree that Cronkite was. The program now reflects Rather's style and priorities, is much less dependent on Washington for its news content, and boasts the strongest and most admired lineup of correspondents and producers in network news.

"Two things I try not to take too seriously are myself and the ratings," Rather said. "On my best days, I succeed."

Last week, Rather typified a relatively new trend in anchordom when he traveled to Middle America to anchor his program out of American farm country, originating one night from San Antonio, another night from Sioux Falls, S.D. There was some chiding of Rather and the program, however, from within news circles, for being in the Midwest when the big story of the moment was occurring in the Far East, where Corazon Aquino was replacing deposed dictator Ferdinand Marcos.

Brokaw thinks Rather and company goofed. "I'm not sure it made sense for CBS to be caught out of position in San Antonio and Sioux Falls when the big story was the Philippines," Brokaw said in response to a question about anchor wanderlust. He thought it did make sense, however, for him and ABC's Peter Jennings to have gone to the Philippines on Election Day there. "We constantly have to be examining a number of factors when we make these decisions," Brokaw said. "The important thing is not to be a slave to your planning."

However, Rather is adamant that the farm country remotes were the right step at the right time. Half-jokingly he notes that "San Antonio and Sioux Falls are closer to the Philippines than are New York and Washington." Brokaw anchored from both those cities last week; Jennings was in Moscow, where he appeared to get a very bad cold. And not a great deal more.

"I think we did the right thing," said Rather. "The farm story is a very good story. It's an underreported story. The carping I hear is mostly, I think, from the established eastern media. They don't understand how important a story it is. That reflects an eastern bias we all like to say doesn't exist, but on some stories, and on this story, it does.

"I have to understand the country to which I am broadcasting. We are a national newscast. I have to get out and talk to people. And for that, we've got no apologies. We covered the Philippines every bit as well as we could have done from New York or Washington."

For Rather, the farm story exemplifies how the "CBS Evening News" with him differs from the "CBS Evening News" with Walter Cronkite -- that there has been a decentralization of the program, with far fewer reports coming from Washington and far more from the rest of the country. He links this change to the challenges to federal authority posed first by Jimmy Carter and then, much more successfully, by Ronald Reagan. He he said the "CBS Evening News" would probably have made the change "if Walter Cronkite had stayed, or if Doo-Wop Diddley had been named anchorman."

Brokaw disagrees. "The technology now makes it easier for us to get out there," he said. "It's the technology that drives that as much as anything." In addition, he said, the fact that local stations have expanded their own evening news time makes it more incumbent on the networks to be creative with their newscasts and flex their production muscles.

Russert said that where "Nightly News" formerly included one "Special Segment" feature piece a week, it now includes one every night. The evening network newscasts are not at all the headline pageants they used to be; now they're more like news variety shows.

Brokaw has ingratiated himself with the viewing public during his anchoring of special events coverage, Russert thinks. "We've achieved parity with the other networks," he said. "There's a certain acceptance of the fact that there are three qualified anchors now, and not one dominant. Having been in third place a year and a half ago, that's very important for us."

Russert suggests that Rather does not have the intensity of anchor loyalty that the grandfatherly Cronkite enjoyed, and that ratings for such special news events as last week's presidential speech on defense bear that out. In 12-city overnights, NBC was in first place, because viewers are accustomed to tuning in NBC at 8 o'clock on a Wednesday night. Normally they see "Highway to Heaven." This night they saw "It Came From the Oval Office."

"The days of Cronkite, and of Huntley-Brinkley, are over," Russert said. "If it's Thursday at 8 p.m. Bill Cosby's time slot , then NBC will win. The ratings on interrupts are very much tied to the entertainment schedule being preempted." NBC's prime-time success has thus led to more exposure for Brokaw. CBS prime time, with its continued appeal to older, less desirable audiences, is on a losing streak that can't possibly help Rather.

Brokaw admits that for him to pooh-pooh Nielsen ratings would have to sound "disingenuous" at best. "Sure, they're important in our lives," he said. "But they're not overwhelming us on a day-to-day basis, or we would have been overwhelmed some time ago. It would be inappropriate for me to say suddenly that ratings are the most important barometer, since when we were losing, I kept saying that they weren't."

Rather is demonstratively sanguine. "Somebody once said, 'The first law of television is that nothing lasts,' and it's true," he said yesterday, just a couple of hours before his broadcast. Continuing in this philosophical vein, he said later, "Somebody once said, 'It's a crazy business,' and somebody was right." Asked if there would be "meetings and shouting and stuff" if the ratings are down in today's Nielsen report, he said, "There are meetings and shouting and stuff whether they go up, down or sideways."

It does irk Rather that while in five years of his anchoring "we've won every year" in the ratings, the only time this gets much press attention is "when one of our competitors draws near." He sighs. "Nobody in this business can be King Canute. You can control some things, but the great forces of nature, and ratings madness, nobody can control."

And that's, it might be said, still the way it is.