President Carter's speech last night on the Soviet troops in Cuba appeared to soften congressional alarm over that issue and to have removed at least one immediate obstacle to Senate consideration of the strategic arms limitation treaty.

The obstacle was the reluctance of the Senate Foreign Relations Committee chairman, Frank Church (D-Idaho), to allow his committee to act on the treaty until the troops issue was resolved. While expressing reservations, Church said last night he will reschedule committee sessions to act on the treaty in the hope of getting it to the Senate floor.

However, neither Church's comments nor the generally favorable reaction to the steps Carter announced last night assured the White House of achieving its long-range objective -- approval of the treaty by the full Senate.

While the president generally was praised for handling the troops issue wisely, his speech to the nation did not appear to have changed any minds among those senators who are lined up either for or against the treaty.

Church, who earlier had said he saw no hope for approval of the treaty so long as the Soviet combat brigade remained in Cuba, was given a private briefing at the White House last night before the president spoke. Emerging from that briefing, he told reporters:

"I think we can salvage the SALT treaty, and I'm looking for a way to do it. I don't think that SALT is scuttled. I believe that a way can be worked out that is satisfactory to the Senate."

Late last night, after the speech, Church issued another, less optimistic statement, suggesting that the presence of the Soviet troops remains a serious obstacle to approval of SALT II. While sticking to his pledge to try to move the treaty to the Senate floor, Church said:

"The Soviet assurances are welcome, but insufficient. If the SALT II treaty is not to be rejected by the Senate something more than Russian representations will be necessary."

"I continue to believe," Church said "that before the treaty may take effect the Senate will insist on an affirmation by the president, backed up by our own intelligence, that Soviet combat forces are no longer deployed in Cuba."

Sen. Richard Stone (D-Fla.), who raised questions about Soviet combat troops in Cuba last summer and was initially told by the administration there were none, called Carter's actions "constructive" but said they did not go far enough.

"The tangibles introduced on the U.S. side are positive, but from the Soviet side there are reassurances and not tangibles," Stone said. "I would have liked President Carter to say we are insisting the combat troops be removed."

Stone said he had not made up his mind on SALT but the debate over the treaty should take place in the context of overall Soviet-American relations.

"This combat brigade is one of many issues to be considered," he said.

In other reactions:

Sen. Walter Huddleston (D-Ky.) said Carter's actions were "adequate and appropriate" and his speech "placed the situation in the proper perspective."

Sen. Lloyd Bentsen (D-Tex.) also said the president had placed the issue "in its proper perspective," adding. "He cut it down to size."

Sen. Charles McC. Mathias (R-Md.) said Carter "spent more time repairing self-inflicted damage than he did in addressing the substance of the Cuban problem." Cuba, Mathias said, is "apparently going to continue to collect $8 million daily from the Soviet Union and warm up its relationship with the United States while it plays host to a military force that creates political problems for the Western Hemisphere."

For the most part, the actions announced by Carter did not appear to have changed many opinions among senators who were either strongly for or against the SALT accord before the troops issue arose.

Sen. John Tower (R-Tex.), a treaty opponent, said the president's speech was not convincing to senators who want to see "some change in Soviet behavior."

"I think the president would be better advised to say that until there is some improvement in Soviet behavior throughout the world we should not consider ratification of SALT," Tower said.

However, Sen. Alan Cranston (Calif.), the assistant Democratic leader and a strong treaty supporter, took the opposite view.

Cranston praised Carter's actions as "reasonable and restrained" and said they should satisfy those who considered the Soviet troops a threat to the United States.

"This has not been the first, nor will it be the last, dispute between our two competing nations," he said. "The real challenge facing us both is to ensure that none of these disputes escalates into nuclear confrontation. Ratification of SALT II is an indispensable step toward containing the nuclear risk. Indeed, the whole disagreement over Soviet troops in Cuba points up the urgency for Senate action on ratification before the end of this year."

A number of presidential candidates responded to the president's speech. The most critical was California's Democratic governor, Edmund G. (Jerry) Brown Jr., who accused Carter of "misguided, highly irresponsible diplomacy."

Comparing Carter's speech uith "President Johnson's early comments on Vietnam," Brown said, "Concealed within the rhetoric of peace we again see the specter of future military intervention."

Without evidence that the Soviet troops pose a threat to the United States, "action on our part is provocative and irresponsible," Brown said.

Republican John B. Connally said he was happy that Carter had "backed away from his earlier overreaction," but was "dismayed that he failed to decisively draw the line on Soviet-Cuban military adventurism throughout the world."

Another Republican presidential contender, Rep. John Anderson of Illinois, praised Carter for keeping a calm perspective, but criticized him for not producing "any real plan or idea of how to deal with either Soviet or Cuban adventurism in other parts of the world."

Before the speech, at least some political figures belittled the seriousness of the issue that led the president to address the country on nationwide television.

"Let's face it, 2,000 to 3,000 Soviet combat troops in Cuba is, to borrow a phrase, a thorn in our side, not a dagger in our heart," said Sen. Edward Zorinsky (D-Neb.).

"No one uith a straight face can seriously suggest otherwise," Zorinsky said in a Senate speech. "There is a ridiculous quality to the issue, and the whole town knows it. But nobody really has the guts to say it."

Republican National Committee Chairman Bill Brock said the whole issue of Soviet troops in Cuba uas "a political charade." He criticized the "irrationality" of making this the issue, rather than the use of Cuban troops to further Soviet interests in Africa.

"We're fighting the wrong battle on the wrong issue in the wrong place," Brock said.