Two of the Senate's top Democrats endorsed President Carter's Middle East peace efforts yesterday, in the wake of criticism from Senate Minority Leader Howard H. Baker Jr. (R-Tenn.) and a general sense of unease among Israel's American supporters.

In separate speeches on the Senate floor, Majority Leader Robert C. Byrd (D-W.Va.) and Sen. Abraham A. Ribicoff (D-Conn.) stressed that even as he raises unpleasant unresolved issues, Carter is committed to Israel's security.

Ribicoff said he trusts Carter, Vice President Mondale and Secretary of State Cyrus R. Vance on the issue "as a United States senator . . . as an American . . . as a Jew."

Carter "has been doubted, questioned, and pressured to prove his commitment to Israel - and he has repeatedly done so," Ribicoff said.

". . . He is talking frankly about final, recognized and secure borders, about full normalization of relations among the countries of the region, and he is talking about the Palestinian question. Simply raising these basic issues raises the level of anxiety.

"But it is the only honorable course for a President of principle and courage . . . Let us support an American President who is doing exactly what he should be doing."

The comments appeared to be part of a Democratic effort to rebut Baker, who charged Tuesday in a speech to the World Jewish Congress meeting here that the administration's Middle East policy was playing "Russian roulette" with world peace and Israel's security.

Baker specifically criticized a joint statement issued last month by the United States and the Soviet Union which set out guidelines for convening a Geneva peace conference on the Middle East.

Carter indirectly took on Baker Wednesday night when, without naming the minority leader, he said in a speech before the same Jewish group that "intemperance or partisanship" could imperil "the best opportunity for a permanent Middle East peace settlement in our lifetime."

Byrd echoed the President's warning against partisanship. "We may find ourselves in disagreement with certain pronouncements . . .," he said "but the important factor is that President Carter is making a genuine and vital effort to establish a framework for negotiations . . . I believe the President's policy . . . is deserving of support."