Congress returns to work following a lengthy Easter recess today still facing major disputes over the two issues that have dominated the legislative session this year -- U.S. policy in Central America and President Reagan's fiscal 1987 budget proposals.

The House Rules Committee is scheduled to meet Thursday to set the stage for a resumption next week of the debate over the administration's request for $100 million in aid to the Nicaraguan counterrevolutionaries, known as contras, who are fighting the Sandinista government.

Meanwhile, Congress appears certain to miss its April 15 deadline for adoption of a fiscal 1987 budget under the new Gramm-Rudman-Hollings budget-balancing law as Senate Republicans struggle behind the scenes for a consensus on the issue.

Majority Leader Robert J. Dole (R-Kan.), caught in a cross fire between the Senate Budget Committee and the White House, has indicated he will spend this week if not longer in consultations aimed at reaching an accommodation. But prospects appear bleak, and no date for Senate action on the budget has been set.

The administration is seeking $70 million in military aid and $30 million in nonlethal "humanitarian" assistance for the contra rebels. The House, by a vote of 222 to 210, rejected the aid package on March 20, but seven days later the Senate narrowly approved a slightly modified version of the aid request.

The Senate-passed measure would delay release of $75 million of the aid for 90 days while the United States sought to arrange regional peace negotiations. However, the $25 million provided immediately to the contras would include funds for military training and defensive weapons, including surface-to-air missiles.

There is a widespread assumption in Congress that some form of contra aid will be enacted, with the main debate centering on what restrictions will be imposed. The House Democratic leadership has pledged to hold a second vote on the issue April 15 during consideration of the fiscal 1986 supplemental appropriations bill.

The Rules Committee meeting Thursday will decide which of several possible compromise versions of an aid package will be offered as amendments to the supplemental appropriations bill on the House floor.

The House Republican leadership is expected to seek approval of the Senate-passed version of the aid measure, while Rep. Lee H. Hamilton (D-Ind.), chairman of the Permanent Select Committee on Intelligence, may propose a resolution calling for a series of economic and diplomatic steps to bring about negotiations but which would not provide aid to the contras.

There is also likely to be a third proposal from the group of moderate to conservative Democrats headed by Rep. Dave McCurdy (D-Okla.).

The White House is objecting to the plan to attach a contra aid package to the supplemental appropriations bill because it opposes spending priorities in the appropriations bill. However, a House Democratic leadership aide said the supplemental appropriations bill was chosen because it is certain to be enacted. "We're giving them a vehicle that's going to pass," he said.

The House's first order of business this week will be a spirited debate and vote on legislation to revise the 1968 Gun Control Act. The Senate, meanwhile, will return to its filibuster-plagued debate over a bill to transfer control of Washington National Airport and Dulles International Airport to a regional authority, marking time as the chamber's leaders try to figure out what to do about the budget.

The Senate Budget Committee three weeks ago approved a bipartisan tax and spending plan that defies the administration by curtailing defense spending, raising taxes and rejecting some of its most severe domestic program cuts. The White House raised strong objections, and 24 of the Senate's 53 Republican members -- most of them conservatives -- have called for major revisions.

But Budget Committee Chairman Pete V. Domenici (R-N.M.) and others contend that a budget cannot be put together with Republican votes alone, especially so long as the White House refuses to compromise on the critical issues of taxes and defense spending.

White House chief of staff Donald T. Regan said yesterday that the administration expects the committee version of the budget to be greatly modified on the Senate floor and suggested that the president and the White House will not become deeply involved in budget negotiations until the summer.

The House Budget Committee has been working on a draft budget plan but is waiting for the Senate to move first. As a result of the impasse, the nonbinding April 15 deadline for adoption of a budget that Congress set for itself in the Gramm-Rudman-Hollings law will almost certainly not be met.