As election dust settles, tests of policy return to center stage; THE CONGRESS

The President's smashing personal victory has left Congress almost untouched. Even as he made his 49-state sweep through the nation, the enormously popular incumbent failed to pull along enough Republicans to give him a working majority in the House of Representatives. In the Senate, the Republican ranks will be reduced by two, for a total of 53.

The result is that any hopes for a second wave of the Reagan revolution similar to the budget-cutting and tax-reduction blitz of 1981 have now been doused. President Reagan will have to deal with a feisty, Democratic-controlled House and a cautious Republican Senate in 1985.

Although the GOP expected to retake the 26 House seats it lost two years ago and thus regain the clout it enjoyed during the first two years of the Reagan administration, it had added no more than 15 seats as of this writing. That is roughly the same result as during the Richard Nixon landslide of 1972, when Republicans picked up only 12 House seats.

President Reagan's coattails have shrunk considerably during the past four years. In 1980 the Republicans took control of the Senate and added 34 seats to their column in the House.

Even as Democrats watched their party go down in one of the worst presidential defeats of the century, they counted the election a congressional victory for their party.

''If there were a repudiation of the Democratic Party, we would have lost (more) seats in the House,'' said Rep. Tony Coelho, chairman of the Democratic Congressional Campaign Committee. Until recently, the California congressman had predicted a loss of only 7 or 8 seats. He said election night, however, that the GOP would need at least 25 to provide President Reagan with a working majority. At press time, reports gave the Republicans 168 House seats, to the Democrats' 267.

''They really like Ronald Reagan,'' Mr. Coelho said of the voters. ''But they did not put his program in.'' He said that voters ''want a check'' on the President. He added said of House members, ''Nobody's afraid'' of the Reagan clout, as they were in the first term.

That apparently is exactly what the Democratic House leaders have in mind for the next four years. Coelho predicted a ''stalemate'' on Capitol Hill. ''That's what the country wants,'' he said. Democratic House Speaker Thomas P. O'Neill Jr. said in a television interview that people wanted the House to be a ''Democratic safety net.''

The House minority leader, Robert H. Michel (R) of Illinois, said after reviewing the GOP gain of only 13 to 15 seats that ''I don't think people should expect too many victories'' for Republican proposals in the House.

It is not yet clear what the legislative goals will be during the next Reagan administration. As a candidate, the President set out only a vague outline, including tax ''simplification'' and reduction of government waste.

To fight the huge budget deficit, he has proposed a constitutional amendment to require a balanced budget, plus a plan to permit the president to veto line items in spending bills. But he will not have enough backers in Congress to ensure passage of such proposals, and neither would have an immediate impact on the federal government's red ink.

Probably the most important domestic proposal will be for a ''flat'' or simplified income tax, which has been seen as a possible way to increase revenues. Such reform ''is not a code word for tax increases as far as Ronald Reagan is concerned,'' said Sen. Paul Laxalt of Nevada, chairman of the Reagan campaign, as he outlined the probable legislative agenda.

The tax issue will almost certainly be contentious on Capitol Hill. Democrats , stung by GOP charges that they are the big taxers, are serving notice that any tax bill will have to originate at the the White House and be championed by Republicans.

Senator Laxalt saw no new round of dramatic cuts in federal spending, since he said the biggest programs, such as social security and other entitlement benefits, have been ''fenced out,'' and ''defense will not be subject to extensive cuts.''

On the controversial issues such as school prayer and abortion, Laxalt predicted, ''I think you'll find the President vigorously pursuing these social issues.'' But Reagan is unlikely to have any more success in these areas than he has in the current Congress.

If the composition of the two congressional houses will remain roughly the same, some key players will not return for the 99th Congress.

Charles H. Percy, chairman of the Senate Foreign Relations Committee, lost his bid for reelection in Illinois, the last in a long line of Senate Foreign Relations chiefs to be defeated. The veteran Republican lost to Rep. Paul Simon. The vacancy puts Sen. Jesse Helms of North Carolina, the controversial leader of the GOP right wing, in line for the chairmanship.

Senator Helms, who won a tight race of his own, has promised North Carolinians that he would instead retain his post as head of the Agriculture Committee. During a recent campaign appearance, he argued that voters should return him to Washington because he was one of only two Agriculture Committee members who came from tobacco-producing states. The other member, he said, was Sen. Walter D. Huddleston (D) of Kentucky.

In a surprise upset, Senator Huddleston lost his seat to Republican Mitch McConnell.

Despite Helms's campaign pledge, there is likely to be widespread speculation that he will move into the prestigious Foreign Relations slot next year.

Although the Huddleston race could be tied to a Reagan victory, in most states the Senate races appeared to go their own way. Tennesseans picked Reagan, but also elected Rep. Albert Gore Jr., a rising moderate star on the Democratic scene, to take the seat of the retiring Senate majority leader Howard H. Baker Jr. (R).

Iowans turned out Sen. Roger W. Jepsen, despite visits by both Reagan and Vice-President Bush on his behalf. They chose one of the most liberal Democratic House members, populist Tom Harkin, for the seat.

In the House, the Republicans toppled veteran Rep. Clarence Long of Maryland, who chairs the appropriations subcommittee that oversees foreign operations. Congressman Long has been a harsh critic of Reagan policies in Central America. The member next in line for the chairmanship, however, Rep. David Obey (D) of Wisconsin, is likely to be equally disapproving.

Another thorn in side of the Reagan White House, Rep. Donald J. Albosta (D) of Michigan, lost his seat to Republican Bill Schuette. Mr. Albosta had led the congressional investigation of ''debategate,'' a controversy in which Republicans in 1980 were charged with obtaining Jimmy Carter's debate preparation papers.