The chief Senate opponent of the superpower medium-range nuclear missile treaty said Wednesday "I'm licked" in efforts to amend the agreement, apparently clearing the way for approval before President Reagan begins his Moscow summit meeting.

"I'm licked in terms of doing anything on the treaty," said Sen. Jesse Helms, R-N.C., as he sat down at a meeting with Senate leaders to work out a procedural tangle that has stalled action on the treaty for more than a week.The move raised hopes among treaty supporters that the pact could be approved for ratification as soon as Friday, and forwarded to Reagan by the time the summit begins on Sunday to give him a stronger position in the talks with Soviet leader Mikhail Gorbachev.

Senate Majority Leader Robert Byrd, D-W.Va., and his Republican counterpart, Sen. Bob Dole of Kansas, had filed petitions Tuesday to limit debate and force it to a vote in time for the summit.

"I'm fairly confident we will be able to finish the treaty Friday or Saturday," Byrd said. But he noted that potential problems still exist, including competing items on the Senate's legislative agenda, such as attempting to override President Reagan's veto of a trade bill.

Reagan left Washington Wednesday for the summit, with a three-day stopover in Helsinki, Finland, en route.

The president was looking ahead to the next arms-control treaty, one he hopes will call for massive reductions in U.S. and Soviet arsenals of intercontinental nuclear missiles. He said he hoped such a pact could be reached before his term expires in January.

"It is the requirements of a good treaty, and not some arbitrary deadline, that will determine the timetable," Reagan said in remarks broadcast on the government's "Worldnet" satellite service.

The treaty, which requires elimination within three years of all U.S. and Soviet nuclear missiles with a range of 300 miles to 3,400 miles, requires 67 votes for Senate approval. Estimates of Senate support for the measure range from 87 to 95 votes, so its ultimate outcome is not in question.

The Intermediate-range Nuclear Forces treaty, as it is known, would result in the elimination of 867 U.S. missiles in Europe, and elimination of 1,752 Soviet missiles.

But Helms and a few other conservatives have sought to delay the measure, raising questions about the validity of intelligence data on the numbers of some Soviet missiles and the crafting of the treaty language. They have offered a series of amendments since the treaty was brought up last week, all of which have been defeated by overwhelming margins.

"Both sides fouled up on this treaty," Helms said during Tuesday's debate. "My conscience will not allow me not to pursue the obvious defects."

But Byrd and Dole filed motions Tuesday to limit the debate, and a vote on that matter was scheduled for sometime Thursday. It was considered virtually certain to win the 60 votes needed to cut off debate, and that would set up a vote on final approval of the treaty for sometime Friday.

Sen. Dale Bumpers, D-Ark., a treaty supporter, said he believed opponents were not attacking the intermediate-range missile treaty but were instead trying to sow doubt about a future treaty cutting long-range missile arsenals.