Members of the Republican National Committee yesterday officially elected Clayton Yeutter as chairman of the beleaguered committee, ending a two-year attempt to convert the RNC into a high-tech political machine.

The unanimous vote to approve Yeutter, currently secretary of agriculture and formerly CEO of the Chicago Mercantile Exchange, represents a return to the selection of establishment Republicans to run the multimillion-dollar party committee. President Bush named him chairman after his previous choice, William J. Bennett, first accepted the job and then turned it down because he wanted to earn more money.

Lee Atwater, the rough-edged operative and blues-playing guitarist who Yeutter succeeds, had been a departure from tradition, a strategist of the front lines instead of a pillar of propriety such as Bush, who served as RNC chairman in the 1970s.

Atwater, a specialist in what he called "driving up the opposition's negatives," had vowed to turn the cumbersome bureaucracy of the RNC into an updated national version of an old-style city organization. However, he has spent little time on the job since last March, when he was diagnosed as having a brain tumor. Yesterday, the RNC voted to give him the ceremonial post of general chairman.

Yeutter has little experience in nuts-and-bolts politics and is expected to be a spokesman for broad party themes rather than a day-to-day tactician.

The contrast is reflected in their academic pursuits. Atwater, after a checkered academic career, has for years been working to complete a doctoral dissertation on the strategy and tactics of negative campaigning. Yeutter got all A's on his way to earning his doctorate in agricultural economics, writing a dissertation on "water resources and water conservation."

In a speech to the committee yesterday, Yeutter appeared to advocate a shift away from just the kind of negative campaigning for which Atwater became famous. "I do hope we can have a very high quality debate of public issues as we move to 1992 . . ." he said. "My personal view is that the public is ready for a higher level of political debate than we have had in many political races in recent years."

Atwater won national notoriety for making an issue of the prison furlough of Willie Horton as part of the Bush strategy in the 1988 presidential race.

Atwater, in addition, always argued that it was critically important for the GOP to keep its conservative wing happy and well-nurtured.

Yesterday, Yeutter took what appeared to be two swipes at conservatives. Addressing those on the right unhappy with Bush's abandonment of his "no new taxes" pledge, Yeutter said "not everyone has expressed happiness with the budget summit debates of last year, but that is not an excuse for sitting on our haunches in 1991 or 1992. What's past is past."

At another point, he said, "We have a lot of ideologues who never accomplish anything. It's great to be pure, but if that means that one doesn't achieve anything, then there isn't a whole lot of regard for ideological purity."

Yeutter's speech was met with polite applause and some ambivalence. Don Devine, a conservative political consultant, said that "whatever he said in his speech . . . he is not one of those center-line moderates, he is a good solid conservative."

Eddie Mahe, an adviser to the RNC, said Yeutter "is not a political mechanic and he is not a political strategist, and he made no effort to suggest he is one . . . . His primary job is to put on a convention and reelect a president." After reporters noted that Yeutter's speech made virtually no "red meat" references in terms of stressing such polarizing issues as taxes and anti-discrimination quotas, Mahe said: "It was not a speech written for audience reaction."

Yeutter, 60, was active in politics in his native Nebraska during the 1960s, helping to elect Norbert Tiemann governor in 1966 and serving as Tiemann's chief of staff for two years. In 1972, he served as Midwest regional director of President Richard M. Nixon's reelection campaign. In 1978, he became president and CEO of the Chicago Mercantile Exchange and over the years has served on the boards of such institutions as the Chicago-Toyko Bank, Winrock International and the Chicago Council on Foreign Relations.