U.S. intelligence reports of a Soviet combat force in Cuba ignited a blaze of speculation yesterday about the potential impact on issues ranging from future U.S.-Soviet relations to next year's American presidential and congressional elections.

The most immediate question centered on whether the situation will adversely affect the drive for Senate approval of the strategic arms limitation treaty, the centerpiece of President Carter's program for detente between the two superpowers.

The alacrity with which two senators facing tough reelection campaigns seized on news of the Soviet force also indicated that if the matter is not speedily resolved it could turn into a campaign issue extending up to the presidential level next year.

In the face of these questions, Carter administration sources stressed that no one can provide any clear-cut answers about the diplomatic, military or political implications of the situation until more is known about the Soviet force and the uses for which it is intended.

But both diplomatic and military sources added that the current situation, involving a relatively small ground force armed with conventional weapons, does not appear to be of the crisis proportions posed by the 1962 faceoff that brought the United States and the Soviet Union to the brink of nuclear confrontation over the stationing of Soviet missiles in Cuba. nlike the 1962 crisis, which involved missiles that could be targeted against major U.S. cities, the sources noted that the new Soviet force lacks the size and strength to be regarded as a potential invader of the American mainland.

Of more immediate concern, the sources conceded, is the possibility that Soviet combat troops could be used in some way to further the violence and political instability affecting Central America and the Caribbean. But, the sources added, such a course also seems unlikely, because it would mean over Soviet military intervention in the Western Hemisphere and a new confrontation with Washington.

For that reason, the sources said administration policymakers are unwilling to speculate about where the situation might lead until they have a response from the Kremlin to their questions about what the Soviets and Cubans are up to. The sources added that they hope for some answers when Soviet Ambassador Antoly F. Dobrynin, who is in Moscow, returns here next week.

In its public statements yesterday, the administration conceded that understandings between Washington and Moscow in the wake of the 1962 missile crisis about the stationing of Soviet forces in Cuba were "directed toward offensive weapons systems" and did not involve "ground forces per se."

But, as State Department spokesman Hodding Carter pointed out, the president publicly has pledged to oppose any Soviet efforts, direct or indirect, to establish military bases in the hemisphere. As a result, the sources said, if the administration concludes, on the basis of further information, that the Soviet force constitutes a "base," the United States will have no choice other than to insist on its removal.

Should the Soviets resist such a demand, the sources admitted, there would be another serious downturn in the zig-zagging course of U.S.-Soviet relations, and SALT could become the most immediate victim of increased tensions.

Even if the matter is resolved, there is a danger that detection of a military force, introduced covertly into Cuba, will provide the treaty's Senate foes with fresh ammunition to argue that the Soviet cannot be trusted to comply with the missile limits placed on them by the treaty.

That point was underscored yesterday by Sen. Richard Stone (D-Fla.), who has been charging for more than a month that the Soviets were staging a military buildup in Cuba.

Stone's leap into the breach demonstrated how the fallout from the situation could spill over from the diplomatic arena into the realm of domestic politics. As a senator seeking reelection from a state only 90 miles from Cuba, Stone showed by his statements yesterday that he intends to be out front in any attempt to use concern about Soviet forces on the island as a campaign issue.

Nor was Stone the only politician who appeared to find some potentially exploitable capital in the situation. The first public word about the Soviet force was revealed Thursday night by Democratic Se. Frank Church at a press conference in his home at Boise, Idaho.

Church, chairman of the Senate Foreign Relations Committee, has been marked by conservative groups as a major target for defeat. They have put him into the toughest battle of his political life,and his action Thursday demonstrated his apparent eagerness to show Idaho voters that his committee chairmanship makes him a powerful Washington insider and a man with the clout to help protect U.S. foreign policy interests.

Should the situation lead to a confrontation between the United States and the Soviets, a lot of candidates for office next year undoubtedly would find it hard to resist the lead taken by Stone and Church. In fact, there even was speculation that Carter, struggling to overcome charges of being a weak and indecisive president, might welcome the chance to prove his ability to get tough with the Soviets.

There was no immediate sign yesterday that Carter and his advisers were thinking along those lines. Instead, the administration's public stance took a relatively low-key form, stressing that while there is reason for concern, more information is needed before intelligent policy decisions can be made.

Although they stressed that it was an "educated guess" kind of speculation, most administration sources seemed inclined toward the theory that the Soviet troops are there to perform the duties of Cuban soldiers fighting in Africa and elsewhere and are not intended for a role outside of Cuba.