President Carter disclosed last night that he received a "very positive" message from Soviet leader Leonid I. Brezhnev yesterday afternoon supporting the U.S. decision to establish diplomatic relations with the People's Republic of China.

Carter said the message from Brezhnev expressed "his understanding that our commitment is to peace in the entire world [and] acknowledging the fact that the American position is that our new relationship with the People's Republic of China will contribute to world peace and acknowledging the fact the proper relationship between major sovereign nations is to have full diplomatic relations."

In an interview with Walter cronkite broadcast on CBS, the president indicated that he will reject a request from Senate Minority Leader Howard H. Baker Jr. (R-Tenn.) to delay beginning the process to terminate the United States' mutual defense treaty with Taiwan until after Congress returns to Washington in mid-January.

Other administration officials confirmed that on Jan. 1 the United States will formally notify Taiwan it intends to terminate the treaty in one year under a process outlined in the treaty.

Baker made his request to Carter yesterday in a telegram, arguing that the termination process hould not begin without consultation with Congress.

In the television interview, the president, citing the Brezhnev message, predicted that U.S. recognition of Peking will not hinder the strategic arms limitation treaty (SALT) negotiations with the Soviet Union or Senate approval of a SALT II accord.

He said he hopes the SALT talks near cmpletion during Secretary of State Cyrus R. Vance's upcoming talks in Geneva with Soviet Foreign Minister Andrei A. Gromyko, and that Brezhnev will visit the United States for a summit conference before Chinese Vice Premier Teng Hsiao-ping's scheduled visit to Washington Jan. 29.

Speaking with reporters at a luncheon, an administration official said that Jan. 15 is the tentative planning date for a Brezhnev-Carter summit conference in the United States. But the official stressed that there is "quite a lot of work" remaining before a SALT agreement is reached and it is far from certain that a January summit could be arranged.

Defending his decision to extend diplomatic recognition to mainland China, Carter said that the People's Republic lacks the military capability to attack Taiwan, where he said the initial shock and concern are subsiding.

"My reports from Taiwan, in the last day or few hours, have been that they studied the agreements with the People's Republic, that their original concerns have been substantially alleviated and I don't think the people of Taiwan are any more concerned about future peace than they were before." he said.

Carter also strongly defended his right to terminate the defense treaty with Taiwan and rejected the contention of critics that there was not sufficient consultation with Congress before he acted.

"My constitutional responsibility in establishing relationships with foreign countries is clear and cannot be successfully challenged in court," he said when asked about legal challenges to his action being considered by congressional opponents.

Carter said that until the final weeks of negotiations there was wide-spread consultation with Congress, where he said the administration's goal of recognizing the People's Republic was widely known and generally supported.He also made clear that he will not reverse the process despite the criticism.

"As of the first of January, we will have relations with and acknowledge the nationhood of China," he said. "And Taiwan will no longer be a nation in the view of our own country."

Sen. Baker's telegram to the White House came after he called the timing and method of the president's decision to recognize Peking "a mistake" "We owe [the Taiwanese] more than this," Baker said.

He is a potentially crucial figure in the Senate debate over new strategic arms agreements with the Soviets, and he has provided invaluable assistance to Carter in earlier foreign policy fights in Congress.

Baker did not indicate yesterday that he felt Carter lacked the legal authority to set in motion the abrogration of the Taiwan treaty. Some conservative Republicans have said the Senate must concur in abrogation, since the Senate approved the original treaty.

Sen. Barry M. Goldwater (R-Ariz.) has promised a court suit on this issue.

Baker's telegram yesterday cited the provisions of last year's International Security Assistance Act, which called on Carter to consult with Congress before taking action on full recognition of Peking.

Privately, administration sources expressed some exasperation yesterday that they cannot openly counter conservative critics who charge that Carter has abandoned Taiwan.

"You've got to understand how much the Chinese have been willing to do here," one senior official said last night, insisting that Peking's tacit approval of arms sales to Taiwan for the indefinite future was an enormous concession, and meant China has abandoned hope of actually sbsorbing Taiwan any time soon.

Several House members who belong to the American Conservative Union yesterday promised to seek congressional action delaying recognition of Peking until the Taiwan treaty is reinstated. They also said the ACU will organize a grass-roots campaign against recognition of the People's Republic.