A politically distracted Congress will straggle back to town Wednesday to face a full agenda of high-voltage issues in a one-month session aimed at wrapping up two years of work and getting members home in time to campaign for reelection.

The stack of unfinished business facing the 98th Congress is high. It includes legislation on issues ranging from defense and military aid for anti-government guerrillas in Nicaragua to civil rights, environmental protection, crime, immigration and Social Security benefits.

Running almost as high are suspicions in each party about what kind of campaign booby traps are being laid by the opposition, creating a mood of edgy restiveness that could ignite or neutralize conflict, according to Republican and Democratic aides.

"It looks like there'll be some rather bizarre shadowboxing," said a Senate Democratic staff member who suspects that each party is more interested in getting home to campaign than in sitting in Washington hatching plots against the other party.

"The Republicans are worried we'll embarrass them the way they embarrassed us four years ago, and our fellows are suspicious too," said the aide. "It's like two guys on a playground fencing around and never landing a punch."

But the potential for campaign mischief-making is almost limitless in such post-convention, pre-election sessions, as presidential candidate Ronald Reagan proved in 1980 shortly after Congress returned from its late summer recess.

In a media event that Democrats remember with some pain, Reagan mounted the West Front steps of the Capitol to join with Republican congressional leaders in denouncing the "legislative chaos" of the Democrats and pledging a new "solemn convenant" of executive-legislative cooperation.

With the tables turned, the Democrats are trying to find a way to embarrass President Reagan on what they call the "hyprocrisy factor," Reagan's call for a balanced-budget amendment to the Constitution despite submitting budgets with deficits hovering around $170 billion a year.

House Budget Committee Chairman James R. Jones (D-Okla.) has proposed legislation urging the president to lay out a plan for a balanced budget next year and requiring him to do so in future years -- even if he has to submit an unbalanced budget as well.

The idea tantalizes many Democrats, including House Speaker Thomas P. (Tip) O'Neill Jr. (D-Mass.), who is expected to hop on the budget issue. The Jones proposal could be passed separately by the House or tacked onto a debt-ceiling extension that must be enacted before Congress quits for the year.

Republicans are not expected to be politically shy, either. They are expected to try to force the House Democratic leadership, through a discharge petition, to consider the balanced-budget amendment. Moreover, House GOP young Turks, who virtually took over their party's platform-drafting at the Dallas National Convention last month, can be expected to continue the guerrilla tactics against the Democrats that elevated them in their party.

But there are forces at work to dull the edges of partisanship. On many issues, the two parties often have found more political profit this year in climbing aboard the bandwagon than in aiming for collisions. Moreover, "there is the overriding desire just to get out of here," said a Democratic aide.

In order to do so, the House and Senate must cut away enough of the partisan underbrush to find common ground on at least some big issues. Also, leaders of both parties desperately want to do so in a way that precludes the type of post-election "lame-duck" session that Congress was reluctantly forced to hold in 1980 and 1982, with dubious results.

Most critical is passage of appropriations bills to keep the government operating after the new fiscal year begins Oct. 1, four days before Congress' scheduled adjournment for the year.

This means passage of as many spending bills as possible (four of the required 13 have been enacted) and approval of a stopgap "continuing resolution" to cover the balance.

The key issue is defense spending, including whether to build a second year's worth of MX missiles, a question that was so much in doubt before Congress left town last month that Republican leaders had to put off a vote to avoid a potentially fatal reversal in the Senate.

A deadlock on defense spending prevailed for much of the three-week session between the July Democratic and August Republican conventions. Senate Republicans refused to back down from their compromise with the administration for $299 billion for defense next year, an after-inflation increase of nearly 8 percent. House Democrats proposed a 3.5 percent increase, then offered to compromise at 5 percent, but Senate Republicans would not budge.

Shortly before the most recent recess began, Senate Majority Leader Howard H. Baker Jr. (R-Tenn.) and other GOP leaders agreed to a Democratic proposal for a congressional "summit conference" to resolve the spending issue, which, if successful, could break several logjams.

The defense dispute has been holding up not only the huge military authorization bill but the overall congressional budget for fiscal 1985. It also has been making it more difficult to pass a defense appropriations bill for next fiscal year, raising the prospect of short-term, stop-gap spending for the Pentagon that could increase costs, hinder military planning and force a post-election session, according to some lawmakers.

In addition to paving the way for passage of the defense measures, a resolution of the dispute could save Congress the embarrassment and potentially troublesome precedent of failing to pass a budget for the first time since enactment of the congressional budget act a decade ago.

Failure to pass a budget was a major problem in 1980, as well, adding to Reagan's campaign arsenal and combining with other sins of omission that forced a post-election session.

The controversial MX issue will have to be resolved separately from the defense budget summit.

The House agreed earlier to allow the Defense Department, which is putting together the first 21 MX missiles, to build 15 more after next April only if Congress votes again to approve the extra weapons. The Senate voted to go ahead with 21 more missiles next year, no strings attached.

But continued production was approved in the Senate when Vice President Bush broke a tie. Chances of getting the production money are regarded as iffy at best in the Senate Appropriations Committee and on the floor. The issue could come to a head in connection with the continuing resolution, and some Republicans suggested last week that the administration may have to accept a delay in further MX production.

Another issue that will have to be resolved, possibly in the continuing resolution, is Reagan's proposal to continue military aid to anti-government "contra" guerrillas in Nicaragua, which the Senate approved and the House rejected.

On other matters, Senate leaders have pledged to push for passage, despite signs of a filibuster, of a House-passed bill to overturn the controversial Supreme Court decision in the Grove City College case, which critics say undermines enforcement of civil rights laws.

There also may be new fights in the Senate over abortion and school prayer. Opposition is expected from opposite ideological corners to proposed restoration of Medicaid funding for abortions in case of rape and incest and to a clause in a House-passed education bill sanctioning silent prayer in schools.

The House is expected to approve Senate-passed legislation to implement Reagan's call for cost-of-living increases for Social Security recipients even if inflation is too low to trigger automatic increases. House-Senate conferees will try again to resolve differences over a bill to ease procedures for people threatened with removal from Social Security disability rolls. Most of the rest of Reagan's agenda for the congressional windup is not expected to go far, however, although Senate Republicans plan to make another stab at passing enterprise zone legislation to help poor neighborhoods.

Chances for the trouble-plagued bill to revise the nation's immigration laws are doubtful, although House-Senate conferees are expected to begin meeting soon to resolve differences over the bill. A key question is whether Reagan, who has complained about costs, would sign a compromise.

Differences over anticrime legislation also have to be resolved.

Several environmental bills are stacked up in the two chambers. A compromise is expected on a bill to strengthen legislation on controlling toxic wastes. A bigger question is whether Congress will brush aside go-slow signals from the administration and expand the "Superfund" for toxic waste cleanup. Action also is possible on clean drinking water legislation.

Reagan's recent veto of legislation to increase funds for the Corporation for Public Broadcasting is expected to trigger another funding effort.

Although the tempo is expected to pick up rapidly, both houses will get off to a slow start this week.

The House will consider a bill aimed at encouraging marketing of generic drugs and providing extra patent protection for "pioneer" drugs. The Senate will consider appropriations bills, possibly a banking deregulation measure and Baker's proposal that Senate proceedings be televised.