Two key senators suggested yesterday that time could soon run out on the Carter administration's plan to get Senate action this year on a new strategic arms limitation treaty (SALT) with the Soviet Union.

However, administration sources revealed that the White House now accepts the possibility that the SALT debate could run into next year, and at least some administration officials say they think this could be politically advantageous for President Carter.

The two senators who commented yesterday were Frank Church (D-Idaho), chairman of the Foreign Relations Committee, which will hold the first hearings on SALT II, and Howard H. Baker Jr (R-Tenn.), the minority leader.

At a committee meeting yesterday Church remarked that there might not be time this year to deal with a SALT pact. Later, speaking through an aide, Church said he had no inside information to this effect, but the he had always felt it would take six months or more from the time a treaty is signed until a final Senate vote.

"Time is running out," Church said later by telephone.

Responding to a reporter's question, Baker said yesterday that he thought the administration has about 30 more days to complete a SALT agreement if it hopes for Senate action this year.

As foreseen now by well-placed Senate sources, the SALT pact might proceed by this timetable: first a delay, after the final agreement in principle, of a month or so, pending completion of a summit meeting and drafting of final treaty language. Then two to four weeks of hearings in the Foreign Relations Committee, plus two to four additional weeks of hearings in the Armed Services Committee. Finally, a floor debate that could easily last two months.

If that process begins with final agreement in principle by the end of April, the two committees would have time to hold their hearings before the Senate's August recess. Returning in mid-September, the Senate could then begin a floor debate.

Until now, the Senate leadership has talked of adjourning for the year early in October, a plan that seems unlikely if the SALT debate is to occur in this season.

The Carter administration until recently subscribed to the theory that the chances for winning two-thirds approval for SALT would be substantially diminished if the Senate had to consider it in the midst of the 1980 presidential primaries.

Recently, however, some in the White House have begun considering the idea that a SALT debate during election year might allow Carter to cast himself as a president of peace and disarmament.