That Ronald Reagan's commanding position in the Republican presidential race may ultimately face only George Bush's challenge was suggested when word passed among Republican governors meeting with John B. Connally.

Thompson, whose tentatvie alliance with Connally began forming one year ago, will entertain Reagan soon at his governor's mansion in Springfield. That will mark the first meeting between them since a chance encounter and brief handshake at an Israel bonds rally in Chicago last year.

Connally's ardent courtship of Thompson had nailed down no hard commitment but did produce this understanding: some time in 1979 -- at least before the first 1980 presidentiall primary election -- Thompson would publicly bless Conally's candidacy. With many top Illinois Republicans (including a national committeeman and the legislative leaders) committed to Connally, Thompson's blessing was intended to accomplish two things:

First, it would enhance Connally's showing in the important Illinois primary March 18; second, it would give Thompson precedence in the Connally entourage, including the possibility of becoming Connally's vice president.

"The trouble is," one Thompson aide told us at the winter session of the Republican governors' conference, "the whole deal depended on Connally producing. Connally has not been able to produce -- not yet anyway."

So thompson has moved to strict neutrality, but with Reagan's candidacy getting Thompson's attention for the first time. Asked why Reagan had not telephoned or visited Thompson since that chance meeting almost a year ago, one Reagan insider said privately: "Thompson hasn't behaved very well toward Reagan. Reagan wanted to show it is not without cost to support an opponent of the front-runner."

The shift in Thompson's attitude demonstrates what the governors have analyzed with near-unanimity: basic weaknesses mark the campaign of the former Democratic governor or Texas.

Connally is the most forceful stump speaker of all the Republican candidates and a wizard at raising funds from corporate America. But dynamism and money have not converted the Republican contest into what Connally has long claimed is just ahead: a two-man race between Reagan and Connally.

What Thompson's men call Connally's inability to "produce" has caused multiple frustrations inside his campaign organization. An example came just before the Florida "preferential" convention when Connally was told by campaign aides that he had narrowed the next day's straw vote to a "neck-and-neck" margin with Reagan.

Exhuberant John Connally immediately informed reporters that an upset might be in the making. Not only did he lose to Reagan by 10 percentage points the next day, but Bush came within striking distance of Connally for a close third-place finish.

In a post-Florida meeting of his campaign organization, Connally demanded tighter discipline and cotrol of his campaign staff. Agreement was reached that he should cool his own rhetoric on the theory that his tough-guy image was adding another negative to the heavy burdens he now carries. "I'm getting an image of coming on tough," he told the governors here. "I'm not coming on tough. I'm only coming on candid.

That self-appraisal may be correct, but it adds one more layer to the apprehension among anti-Reagan governors that Connally is not close to overtaking Reagan, leaving only long-shot Bush.

Almost all of the many Republican governors in the political center -- Pierre dePont of Delaware, William Millien of Michigan, Robert Ray of Iowa, Richard Thornburgh of Pennsylvania and others -- view a Reagan nomination as political chicken pox. But every one of them clings to the strict public neutrality they have followed since their session one year ago.

Now Thompson, who had allowed himself to be wooed by Connally, is seeing John Connally is the sharpest political sign yet that the governors are looking elsewhere if anybody is to stop Ronald Reagan.