President Ford and Vice President Rockefeller yesterday threw their political weight behind the candidacy of former Ford campaign chairman James A. Baker III of Texas as chairman of the Republican National Committee.

GOP sources said Ford made his views known in a noontime telephone call to the present chairman, Mary Louise Smith. A White House official while emphasizing that the choice would be made by the national committee predicted subsequently that Baker would be elected chairman.

"I will favor whoever the President supports," Rockefeller said later in the day. New GOP National Committeeman George L. Hinman, a Rockefeller stalwart, already has sent out a letter to committee members urging the election of Baker.

Ford and Rocefeller did not prevail upon two other prominent Republicans, Ronald Reagan and John Connally, to support Baker at a closed-door White House summit meeting. Both Reagan and White House aides agreed that there was no effort to reach a consenus at this meeting, apparently because everyone in the room knew there was no chance of doing so.

"We made no progress at all [on selecting a chairman], and we didn't intend to," Reagan said after the meeting. "That's the function of the national committe."

A White House official confirmed Reagan's comment but said that Baker's name was discussed in the meeting. Historically, GOP national committees have been responsive to the wishes of Presidents in such matters a point made by Rockefeller in his support of Baker.

"The choice is up to the national committee, but the tradition has been that where you have a vacancy to be filled during the term of an incument President, the President is consulted," Rockefeller said.

The vice President did not mention Baker by name and said he would not name anyone until Ford publicly had announced his own choice. Asked why the President declined to do this or to make any statement after the summit meeting, an aide said Ford "didn't want to appear to be dictating to the national committee."

Whether the tradition of approving a President's selection will prevail this time still remains open to question.

The nominal leader of the seven-candidate field is Utah GOP Chairman Richard Richards, who has Reagan's tacit backing and Western support that reaches beyond the Reagan camp. But even Richard's backers acknowledge that he is far from a majority of the 162-member committee thatwill convene in Washington on Jan. 14.15 to choose a chairman. Furthermore several members of the committee believe his strength has peaked at just under 50 votes.

Other candidates former Tennessee Sen. Bill Brock, former GOP senatorial committee executive director Buehl Berentson, presidential urban affairs assistant Arthur Flecher. Indiana GOP Chairman Thomas S. Milligan and Robert Carter. District of Columbia national committeeman and the party's co-chairman.

Carter, who is well-known to the national committee, has been mentioned as a compromise choice who might be acceptable to all factions it none of the front-runners can win a majority.

The President's action yesterday gave strong impetus to Baker, however, and may presage a Baker-Richards showdown in the balloting.

Meanwhile, in the Senate an aide to one of the senators who backed Tennessee Sen. Howard H Baker's surprise victory as minority leader Tuesday said that he received liberal support "because they see him as a middle-of-the-road counterbalance to a possible Reaganite takeover of the national party machinery."

Sen Charles McC. Mathias (R-Md.), a leader of the Howard Baker forces, said this overstated the case but acknowledged that the counterbalance argument "was a sort of general thingin the background of some people's minds."