When the Senate returned from its Thanksgiving recess this week, it found the legislative equivalent of a ticking time bomb on the floor of the chamber.

It was a resolution, filed under the 1973 War Powers Resolution, that could force termination of the Reagan administration's tanker-escort operation in the Persian Gulf on Dec. 20 unless Congress voted in the meantime to authorize continuation of the operation.

For the past several days, Senate leaders have been circling warily around the resolution, searching for ways to defuse it without having to reopen a long-running dispute over application of the war-powers law to the Persian Gulf escort operation.

An abortive attempt to resolve the issue without further fuss was made at the end of Senate business last night; another attempt will be made today. Under consideration is a two-step move -- the pending resolution would be set aside but procedures would be changed to make it easier to get a vote by the full Senate to invoke war-powers constraints in the future.

The Senate's latest tangle with the War Powers Resolution came about in this way:

Six weeks ago, the Senate, torn for months over both the escort operation and whether to apply war-powers constraints to it, thought it had resolved its immediate problem by postponing any definitive votes on the issue until next year.

But not long afterward, Sen. Brock Adams (D-Wash.), who is among a handful of senators who contend the war-powers law should be obeyed as long as it is on the books, filed a resolution to authorize continuation of the gulf escort operation for six months in accord with provisions of the law.

The Senate Foreign Relations Committee considered Adams' resolution last month and shelved it, or so it appeared at the time. No one paid any more attention to it, except Adams, who had come upon a precedent set during the 1983 debate over deployment of U.S. troops in Lebanon that could be used to trigger the law by the simple filing of an appropriately drawn resolution by one member of Congress.

Under the law, the president is required to notify Congress when U.S. troops face "imminent hostilities," beginning a process that ultimately requires approval of Congress to continue engagement of American forces for more than 60 days, or 90 days if the president requests additional time.

But Reagan, like other presidents before him, has cited constitutional and other objections to the law and refused to file the formal notifications required to trigger the deadlines. As a result, Congress has tried on many occasions, most recently in connection with the Persian Gulf tanker-war, to force the president to act or to invoke the war-powers sanctions on its own.

In three months of haggling over how to deal with the War Powers Resolution in connection with the gulf hostilities, the Senate dealt with the issue in every way short of no-nonsense compliance with the law. One reason for the circuitous maneuvering was that the law's deadlines, once triggered, would eventually force Congress to assume responsibility for continuing or terminating the operation, a responsibility that many lawmakers were reluctant to assume.

The maneuvering had become so complex that Adams' move escaped notice largely because of its straightforward simplicity. All he did was file a resolution patterned after one introduced in 1983 by then-Sen. Charles McC. Mathias Jr. (R-Md.) that became the vehicle for authorizing U.S. troops in Lebanon for 18 months. With the help of a parliamentarian's ruling at the time, the Mathias resolution was interpreted as triggering protections -- and deadlines -- of the War Powers Resolution that are aimed at preventing delay and obstruction.

Adams' resolution popped out of committee Nov. 19, just before the recess. It was awaiting the Senate when it returned Monday.