The rift between Senate Republican leaders and Defense Secretary Caspar W. Weinberger widened yesterday as Weinberger continued to resist reductions in the military buildup and key lawmakers indicated that they will try to freeze defense expenditures at current levels.

After what was described as a "tough" meeting between Weinberger and the Republicans at the Capitol, Senate Appropriations Committee Chairman Mark O. Hatfield (R-Ore.) called Weinberger a "draft dodger in the war on the federal deficit," vowed to press for a defense spending freeze, predicted that it would pass and warned of a tax increase if it fails.

Assistant Senate Majority Leader Alan K. Simpson (R-Wyo.) said there was "some very clear unanimity that the defense budget will be frozen" and implied that it was nearing time for the Senate to move ahead on its own.

Asked if the situation is "getting down to the wire," Simpson said the Senate was nearing the point where "you finally have to quit talking the talk and start walking the walk."

Senate Finance Committee Chairman Bob Packwood (R-Ore.) suggested that such a move could come as soon as today, when he said Senate committee chairmen plan to meet to begin taking action on specific aspects of a budget-cutting plan.

In addition to a reiteration of earlier warnings that intransigence on defense could jeopardize the deficit-reduction effort, some senators suggested yesterday that it also could jeopardize continued Republican control of the Senate after the 1986 elections, when 22 Republican seats will be contested.

"I hope Cap Weinberger and Ronald Reagan understand that we are going to need some give on their part to protect the Republicans in 1986," said Sen. John Heinz (R-Pa.), chairman of the National Republican Senatorial Committee. "Putting them between a rock and a hard place is not going to help them."

While insisting that the Republicans had not reached an open break with Weinberger, several senators said they will not be deterred from pushing for big defense spending cutbacks by Weinberger's adamant opposition to such action.

Contending that the impasse can be broken, Sen. John H. Chafee (R-R.I.), who is third in the Senate GOP leadership hierarchy, said, "I see it being overcome by us adhering to our views and the administration recognizing we are dead serious about it."

Others said Weinberger had been warned in "straightforward" terms that President Reagan risks losing the domestic spending cuts he wants if Weinberger won't compromise on defense, an echo of an earlier warning from Majority Leader Robert J. Dole (R-Kan.) that drew a testy response from a Weinberger spokesman.

Several Senate committees have indicated that they are willing to make their quota of spending cuts to achieve a three-year goal of cutting deficits by half to less than $100 billion but that they will do so only if other committees, including Armed Services, make similar cuts.

Among them is the Senate Fiance Committee, which has been allotted the biggest single share of cuts, totaling $65 billion over three years.

"We are prepared to meet our budget totals if -- and it's a big if -- the others come up with their share," Packwood said.

A plan being studied by the Senate leadership would freeze military as well as domestic spending for one year and make permanent cuts in many programs, which together would meet the goal of more than $260 billion in cumulative savings by fiscal 1988.

A one-year freeze in defense spending authority would cut $20 billion from anticipated Pentagon outlays of $286 billion next year, with cumulative savings of more than $100 billion over three years.

By contrast, the administration is expected to propose $8.7 billion in defense spending cuts next year in the budget it is sending to the Hill, adding up to $28.1 billion over three years.

Support for a defense spending freeze appeared to have cooled after Weinberger launched a full-scale offensive against it and it ran into strong opposition from Armed Services Committee Chairman Barry Goldwater (R-Ariz.) and Sen. Ted Stevens (R-Alaska), chairman of the defense appropriations subcommittee.

Although Stevens argued vehemently against a freeze in yesterday's meeting and Goldwater again indicated opposition, the idea appeared to be born-again after the half-hour closed-door session in Dole's office. But some Senate sources cautioned that a freeze may still be too drastic for many Republicans' tastes and indicated that the tough talk was aimed largely at persuading Weinberger and Reagan to soften their positions.

A meeting between Weinberger and all the Republicans senators that followed his session with the leaders reportedly was inconclusive. There was little discussion of specific cuts, and "we never got to a crossing of swords," said Packwood.

In the meeting with the Senate leaders, Weinberger reportedly repeated his contention that the full military buildup was necessary for national security and for a strong U.S. position in arms-control talks with the Soviet Union.

Weinberger and Stevens reportedly also expressed concern that extensive defense spending cuts would relieve pressure for domestic cuts, especially in the Democratic-controlled House. Chafee took note of this argument and said the Senate intends to propose deep cuts in domestic as well as defense spending.

Weinberger was described yesterday as offering no hint of compromise -- a "very conscientious objector," as Hatfield described him.

"The problem is of such magnitude it calls for full mobilization and Cap Weinberger can't be a draft dodger," Hatfield said. "He has to be a participant in this exercise. We can't exempt the military . . . . If we do , we may as well face the inevitable of a tax increase, a substantial tax increase in the very near future."

Senate Republicans have said a tax increase will not be included in the deficit-reduction package but have not ruled it out as a "last resort."