Chances brightened Friday that the medium-range missile treaty will be ratified before this month's U.S.-Soviet summit in Moscow as Senate leaders reported they are favorably impressed with the anti-cheating bargain struck by negotiators for the two superpowers.

The reaction could set the stage for the opening of debate by the full Senate the middle of next week, perhaps earlier.But Majority Leader Robert C. Byrd, D-W.Va., said he will not formally schedule that debate until the Senate's Foreign Relations, Intelligence and Armed Services committees hold hearings and vote their approval.

"I want to hear what the chairmen and ranking Republican members of these committees have to say following these hearings," Byrd said. "They are the experts in this field."

Secretary of State George P. Shultz is to testify before the Foreign Relations Committee on Monday afternoon on the agreement he reached in Geneva with Soviet Foreign Minister Eduard Shevardnadze.

In Brussels, Belgium, Shultz said Friday settlement of a last-minute dispute with the Soviet Union over compliance with verification provisions had strengthened the intermediate-range missile treaty.

Shultz stopped over in Brussels Friday on his way home from Geneva to brief the NATO allies on the fine points of the treaty, which would abolish an entire class of missiles with ranges of 300 to 3,400 miles.

The Armed Services and Intelligence committees announced they will hold a joint meeting late Monday afternoon.

Following a 90-minute luncheon briefing by White House national security adviser Colin Powell, Byrd told reporters that Senate leaders were told that the agreement represents a step forward.

"General Powell feels that the agreements that have been reached are significant and enhance the national security interests of our country," Byrd said.

Senate Republican leader Bob Dole of Kansas quoted Powell as saying Byrd's decision last week to postpone Senate action on the treaty while negotiators addressed concerns that the Soviets were backing away from effective implementation of the on-site inspection provisions of the treaty "did make a difference."

Other senators who attended the briefing also said the results of the Geneva talks seem constructive.

"I'm optimistic we can move ahead," said Sen. Claiborne Pell, D-R.I., chairman of the Foreign Relations Committee.

"I think at this moment there is more optimism for the passage of this treaty than at at any other time

during this long process," said Sen. John Warner, R-Va., the ranking GOP member of the Senate Armed Services Committee.

Warner said the Soviets were "very cooperative" and changed their position to meet U.S. objections on every issue that was raised.

"I'm confident my colleagues on Monday will come to a similar conclusion," he said.

Some senators said there is now at least a possibility the Senate will consent to the ratification of the treaty by the time President Reagan and Soviet leader Mikhail S. Gorbachev convene their Moscow summit on May 29.

The two leaders signed the Intermediate-range Nuclear Forces treaty, providing for the total elimination of U.S. and Soviet mid-range missiles, in Washington last December.

Sen. William Cohen, R-Maine, the Intelligence Committee's vice chairman, said the issues raised about Soviet implementation of on-site inspection to verify compliance with the treaty were "by no means mere technicalities."

"I believe that as a result of raising these issues we were able to resolve them satisfactorily," Cohen told reporters.