Capital's adversaries find middle ground. Onrushing events have created a wave of compromise in Washington, with Democrats and Republicans laying aside their political hatchets to deal with the budget deficit, the impending Gorbachev visit, and other pressing matters.

A spirit of compromise is stealing a march on events in Washington. For the first time in a year, Congress and the White House are holding their respective noses and working together.

Thank the stock market crash, the impending visit of Soviet leader Mikhail Gorbachev, a couple of Supreme Court nominations that went sour, and the march of events in Central America.

Across a spectrum of issues over which Congress and President have long quarreled, the two sides have temporarily put aside their differences and declared a truce. (Compromise on ABM Treaty, Page 6.)

Few of the erstwhile combatants have evinced a change of heart on these subjects. Democratic and Republican partisans seem divided as ever in their basic beliefs about the wisdom of nuclear weapons testing, raising taxes, or financing the Nicaraguan contras.

But cooperation has become a new priority, if only because of a realization that continued stalemate on these matters threatens to wreak havoc with American policy abroad, disrupting relations with ally and adversary alike.

Lawmakers and administration officials consider such disruptions to be particularly costly now, as the United States seeks to contain its budget deficit and reassure jittery investors in Europe and Asia; enter into sweeping arms control agreements with the Soviet Union; and supervise the implementation of democratic reforms in Nicaragua.

Thus, the White House and the Democrat-controlled Congress have been driven together.

``It is a situation where all sides have felt there really isn't any other choice,'' says Sen. Nancy Kassebaum (R) of Kansas.

Congress and the White House were set on a collision course after Democratic leaders attached some arms control provisions to this year's defense spending bill. Democrats had been pushing legislation to ban nuclear weapons testing, force continued US compliance with the SALT II arms control treaty, and stall deployment of the space-based Strategic Defense Initiative by enforcing a restrictive interpretation of the 1972 Antiballistic Missile Treaty. President Reagan threatened to veto any bill containing such legislation.

For 10 months, neither side budged.

Then came inklings that Mr. Reagan would play host at a summit with Mr. Gorbachev to sign a treaty banning the deployment of intermediate-range nuclear weapons in Europe.

On Tuesday, congressional leaders announced that the stalemate had been broken. The administration had accepted language in the defense bill forcing it to stick with the ABM Treaty's narrow interpretation. Democrats agreed to drop the nuclear test ban idea. White House officials said President Reagan would sign the bill.

``We didn't want to be fighting with each other while the administration was trying to negotiate with Gorbachev,'' says Rep. Les Aspin (D) of Wisconsin, chairman of the House Armed Services Committee.

The White House has gritted its teeth and tried to appear conciliatory on Central American policy. Last week relations between House Speaker Jim Wright (D) of Texas and the Reagan administration plummeted after Mr. Wright met with Nicaraguan President Daniel Ortega Saavedra.

The administration, which has refused to meet with Mr. Ortega, considered Wright's actions to be an unconscionable intrusion on its prerogatives.

Administration officials blasted Wright in the press. But there were signs that those tactics had begun to backfire.

Some Southern Democrats began to resent the personal attacks on Wright - the same Southern Democrats who had supported the administration's past contra aid proposals.

``Attacking Wright was the smartest thing the administration had done since appointing Ginsburg,'' jests Rep. Barney Frank (D) of Massachusetts, referring to the administration's abortive effort to seat Judge Douglas Ginsburg on the Supreme Court.

In an effort to mend fences, Secretary of State George Shultz made an extraordinary trip to Capitol Hill to cosign a six-point statement with Wright pledging to work together and not to ``create unnecessary problems.''

Perhaps the most dramatic turnaround has occurred in this year's battle of the budget. Until world financial markets took a plunge last month, Democrats and Republicans seemed immovable, and an automatic budget cut by the Gramm-Rudman deficit-reduction act seemed inevitable. The market crisis, however, spurred a clamor at home and abroad for an agreement to reduce the deficit.

For nearly four weeks, 14 lawmakers, three administration officials, and many congressional and White House staff members have tried to oblige in a small room in the Capitol building.

At this writing, they appear ready to close on an agreement that would raise taxes, cut defense and domestic spending, and lop about $30 billion off this year's deficit - an achievement that falls short of recent expectations but one that, earlier, few would have expected was possible.

Says one of the negotiators, Sen. Bob Packwood (R) of Oregon: ``The markets made us do it.''