Washington — In only a few days, Congress will scatter to the 50 states to begin election campaigns in earnest. Meanwhile on Capitol Hill, another congressional campaign is reaching a high point.
Five Republican senators are knocking on office doors, sending out campaign letters, and making speeches in hopes of wooing their own colleagues. They are vying for the leadership post of retiring Senate majority leader Howard H. Baker Jr. (R) of Tennessee. And because this week is the final one for senators to be gathered in one spot until they choose a new leader Nov. 28, the mostly private campaign is breaking out all over Capitol Hill.
Item. Sen. Richard G. Lugar of Indiana, one of the candidates for Republican leader, has dashed off a news release with the information that on Oct. 2 he praised fellow Republican Sen. Charles H. Percy as a ''great chairman of the Foreign Relations Committee.''
Item. Sen. Ted Stevens of Alaska, another candidate, submitted this week what amounts to a platform by proposing a major overhaul of Senate procedures.
Item. Two other hopefuls, Sens. Robert Dole of Kansas and James A. McClure of Idaho, were visible on the Senate floor, trying to resolve a civil rights debate that tied up the Senate for nearly a week.
The fifth candidate, Sen. Pete V. Domenici of New Mexico, made his rounds to senatorial offices in private. He's being ''very very quiet'' about his campaign , says an aide.
Probably the most unpredictable race of the political season, the election for Republican Senate leader is largely a clubby affair. Since the vote will be by secret ballot at a closed-door meeting, even the candidates cannot be sure their supporters will hold firm.
But the outcome will have an important effect on the Senate's atmosphere and its relations with the White House for the next four years. And since the Senate is expected to remain Republican, the winner of the leadership race will move into the national spotlight.
Probably the best-known senator in the race, Mr. Dole, has often served as mediator between liberals and conservatives. He apparently failed to pull out a compromise this week over a proposed antidiscrimination measure. But he won much of the credit for bringing all sides, including the White House, aboard to pass a key Voting Rights Act extension.
Dole, chairman of the powerful Senate Finance Committee, is known not only for his legislative craftsmanship but also for his dry wit. And he is the only candidate with a direct tie to the Reagan administration, since his wife is Transportation Secretary Elizabeth Hanford Dole. However, the famous Dole wit is at times sharp, and despite the connection with the White House, his relations have not always been cosy with the Reagan administration.
The biggest question hanging over the Dole bid for the leadership post is whether senators want a leader who has undisguised presidential ambitions.
A yen for the White House should not disqualify Dole, said fellow contestant Senator Lugar in an interview. But Lugar, who chaired Senator Baker's brief presidential campaign in 1980, added that Baker's leadership role in the Senate ''debilitated his national ambition.''
Lugar, who chairs the National Republican Senatorial Committee, oversees the party's campaign to keep the Senate majority it won in 1980. He says his qualifications for leader include his experience as mayor of Indianapolis and his smooth relations with the Reagan administration.
The Indianan, who has sent a formal and detailed campaign letter to his colleagues, says many of the Republican senators are not interested in the leadership question yet. Some ''don't even want to discuss it'' until after the Nov. 6 election, he says. That date could be particularly important for the Lugar bid, since he will receive at least some credit or blame for how Republicans running for the Senate fare at the polls.
Senator McClure, who is the candidate of the conservative wing of his party, holds that the biggest problem in Congress is the ''confrontation between the House and Senate,'' which he calls ''an absolute deadlock on fundamental issues.''
Asked if the selection of a conservative leader might exacerbate that problem , he counters, ''I may be the perfect guy. You've got the most liberal leader in the House (Democratic Speaker Thomas P. O'Neill Jr.). I may be the most conservative leader in the Senate.''
He could be the best Senate leader for striking a compromise, McClure suggests.
But the Idaho senator, who chairs the Energy and Natural Resources Committee, also argues that political philosophy is a minor issue in the race, since for senators it is more important to know that ''their rights will be protected'' in Senate action.
McClure and Lugar speak of the need to reform Senate procedures, a theme that has been foremost in the campaign of Senator Stevens, who now serves as assistant Republican leader.
At a lunch recently Stevens conceded his own weak points.''I'm from an offshore state,'' he said. ''I'm known as being provincial.'' He pointed out that much of his legislative career has been occupied with Alaska pipeline and Alaska lands issues.
Stevens says that as he talks to his colleagues ''many have asked me (if) I can be a national spokesman.''
He focuses on the loose procedures that have allowed the Senate to tie itself into knots in recent days. He has proposed reforms to cut off delay tactics and streamline Senate action.
Senator Domenici, meanwhile, is saying little in public. He rose from his back-bench role as a little-known member of the minority in 1980 to become the chairman of the Budget Committee and one of the bright stars of the Senate after the GOP took control.
A Republican of slightly moderate stripe, Domenici has managed to support the Republican administration while remaining popular in a Democratic state.