Congress: twilight brinksmanship. As adjournment nears, lawmakers press their causes

If you believe the experts, Congress will wrap up its business for the year sometime around the middle of next month. And just what is that business? ``Our business,'' says Senate Republican whip Alan Simpson (R) of Wyoming, ``is to pass appropriations bills and get out of here.''

Well, yes. Congress's primary task is to pass a half dozen bills that will fund thousands of federal programs during the new fiscal year commencing Saturday. But lawmakers are rarely content to limit themselves to primary tasks - especially in so politically superheated an environment as that preceding a presidential election.

So, for example, the Senate is presently knotted up over a Democrat-drafted bill to raise the minimum wage. The legislation had languished for months, a victim of White House opposition and Democrats' reluctance to engage the Republicans in a minimum-wage debate during the campaign season. Ironically, it was an official in the Reagan administration - Vice-President George Bush - who resurrected the measure earlier this month by stating that he would support a slight increase in the wage.

That was enough to spur Senate Democrats into action. Their bill would raise the wage floor from $3.35 to $4.55 an hour over the next three years. Republicans have fought back, championing a proposal that would allow employers to provide for new hires a ``training wage'' at 80 percent of the minimum wage. At the same time, they have wielded the rules of the Senate to stall debate and prevent the Democrats from bringing their bill to an actual vote.

Likewise, Democrats plan to push ahead with legislation guaranteeing parents unpaid, job-protected leave to take care of newborn or sick children - again, after a tacit endorsement of the concept from Mr. Bush.

Presidential politics may also affect the fate of critical legislation funding the military during the upcoming fiscal year. The White House began bargaining with congressional Democrats Friday over the future of arms control provisions in a bill opposed by President Reagan.

At issue are sections that would constrain development of space-based defenses, force compliance with certain controversial sections of the Anti-Ballistic Missile and SALT II treaties with the Soviet Union, and reduce the administration's funding request for the rail-based MX missile. Those provisions were included in an earlier defense bill, thus prompting a presidential veto. The veto, in turn, prompted Democrats to attach the offending measures to the present defense appropriations bill.

A compromise between the administration and congressional Democrats will have to be found by the end of the week. If an agreement cannot be reached, the executive and legislative branches will find themselves embroiled in another end-of-the-year veto confrontation, possibly requiring another stopgap spending bill to tide the Pentagon over for a few months.

The presidential race and the approaching end of the congressional session are providing other opportunities for political brinksmanship as well. For instance, a Democrat-sponsored bill that would cut off nearly all trade between the US and South Africa is expected to pass out of the Senate Foreign Relations Committee this week. What happens after that, however, is anybody's guess. Many Democrats consider the legislation excessive, and a number of Republicans have put out the word that they will force politically awkward defense and foreign policy votes on Democrats if the bill reaches the Senate floor.

And in less noted ways, politicians play ``chicken'' at the end of a session. The House, the Senate, and the Reagan administration have endorsed legislation that would allow the US to join the Berne convention, a century-old copyright pact. But one of the bill's sponsors, Sen. Strom Thurmond (R) of South Carolina, recently told Senate majority leader Robert Byrd (D) of West Virginia that he would sidetrack the treaty. The reason: Senator Thurmond was irritated that 35 Reagan administration judicial appointees had yet to be considered by Democrats of the Senate Judiciary Committee.