House and Senate Democratic leaders predicted yesterday that mandatory balanced-budget legislation will pass, but said they will adamantly resist "shotgun-to-the-temple" efforts by Senate Republicans to force a quick vote on the issue.

Their predictions came as the GOP-controlled Senate, forced into an extraordinary weekend-long session by Majority Leader Robert J. Dole (R-Kan.), prepared to vote today on whether to choke off debate on the legislation.

Dole and other GOP leaders are seeking to attach the proposal to legislation needed by Monday to raise the federal debt ceiling from $1.8 trillion to $2 trillion, using the deadline pressure of the debt measure as leverage to force action on the budget plan.

Stepping up his hard-line tactics, Dole said he is prepared to see a few days of financial disruption -- triggered when the government runs out of borrowing authority and can no longer pay its bills -- rather than bow to Democratic demands for a brief stopgap debt-limit extension to allow more time to consider the budget plan. Delay would only increase opposition, he said.

"The government won't come to a halt but it may slow down a bit. My view is the stakes are high enough you may have to put up with it disruption for a while," Dole said. But he later indicated that he may have to accept a short-term extension at some point.

President Reagan, who endorsed the budget proposal Friday, also stepped up pressure for its adoption, using his Saturday radio address to characterize it as potentially "historic." But he also added a "caveat," reiterating his insistence that Congress adhere to defense compromises calling for military spending increases of 3 percent over inflation for the next two years.

Although specific provisions of the budget plan came under increasingly strong Democratic attack during a day-long debate on the issue, both Senate Minority Leader Robert C. Byrd (D-W.Va.) and House Majority Whip Thomas S. Foley (D-Wash.) said they thought legislation to force a balanced budget within a few years would ultimately pass.

"It's not a question of if or whether but how," Byrd said. There is a "great likelihood" that some kind of budget-balancing plan will be enacted, Foley said.

Both reiterated support for principles behind the legislation but questioned whether it would give the president too much power and complained that it would unduly squeeze social welfare programs.

The proposal, advanced by Sens. Phil Gramm (R-Tex.), Warren B. Rudman (R-N.H.) and Ernest F. Hollings (D-S.C.), would set fixed limits to force deficits down from $180 billion next year to zero by fiscal 1991. If the targets are not met, the president would be required to cut spending, generally along benchmarks established by Congress, to bring outlays in line with the deficit ceilings.

During yesterday's desultory debate, which drew only a handful of participants, senators argued over how the new budget controls would work, and many complained that its implications were unclear at best.

"Few senators, including sponsors of the measure, really know what they're doing," said Sen. Gary Hart (D-Colo.), a critic of the proposal.

Democrats also argued that the constraints were unduly rigid for periods of recession, possibily threatening chances for economic recovery.

But some of the harshest criticism came from a Republican, Sen. Lowell P. Weicker Jr. (Conn.), who characterized the plan as a GOP effort to "save face on a discredited economic policy" of tax cuts, defense spending increases and a resulting surge in deficits. It was, he said, "like Napoleon after Moscow inviting you to join him at Waterloo."