Washington — In the elegant and cozy old Senate chamber, lined with four fireplaces and crowded with dark wooden desks in a tight semicircle, Daniel Webster and John C. Calhoun once declaimed.
This week in the rarely used Capitol room that was home for the ''golden era'' of senatorial oratory, 53 Republican senators will determine in utmost secret who will lead the US Senate for the next two years. The vote will close the era of genial and conciliatory majority leader Howard H. Baker Jr. of Tennessee, who is leaving the Senate after four years at the helm.
No one can be certain what kind of new era will be launched on Wednesday when the secret balloting is over and one of five candidates emerges as Mr. Baker's replacement.
''It's terribly private,'' says Sen. Alan K. Simpson (R) of Wyoming. ''It's vexacious to people,'' he adds, a little amused at the frustrated outsiders and reporters who want to know who is ahead. But, Senator Simpson adds, ''There isn't any more to know.''
Sen. Arlen Specter (R) of Pennsylvania calls the intense and private campaign ''innervating. I think most of us 53 Republicans really believe we have five outstanding candidates. We're really being asked to choose one brother over another.''
For all the privacy of the vote, the direction of the new leadership will have a very public effect. Not only will the Senate leader largely determine the success of President Reagan's program in the vital first few months of his second term. The new leader will also be called to position the GOP so that it can retain the Senate majority in 1986, when 22 Republican seats are up for reelection. As the candidates scurried around last week trying to pin down votes , it was virtually impossible to determine the front-runner.
When the 53 gather for the secret balloting, they will pick among five members with distinct styles and viewpoints.
Sen. Robert Dole of Kansas. The best-known nationally, he ran for vice-president with President Gerald Ford in 1976.
When the Republicans chose Senator Baker as their minority leader in 1977, it was partly because he was an articulate national spokesman for the party. If they want such a national figure this time, Mr. Dole would be the obvious choice. A centrist, he is one of the most skillful legislators on Capitol Hill and seems to relish the job of forging compromises in the midst of seemingly impossible disputes. He is not always successful, as in a recent civil rights dispute, when his 11th-hour plan failed.
Senator Dole, known for a wit that can be sharply barbed, would probably be a more forceful leader than was the genial Baker. But it is far from clear that the independent-minded senators want such leadership. Although personal relations are more important than philosophy in the choice of majority leader, Senator Dole has differences with some in his party over taxes. As chairman of the Senate Finance Committee, he does not go along with Republicans who oppose any tax hike next year. Senator Dole has also made no secret of his hopes to someday live in the White House.
Sen. Pete V. Domenici of New Mexico. Should the Republicans want a strong leader who is less distracted by hopes for the presidency, Senator Domenici could be their choice. Serious-minded and a tireless worker, the chairman of the Senate Budget Committee has been a voice for realism in the chaotic budget process. He put together the Reagan budget victories in 1981, but since then he has feuded with the White House over the mounting federal deficits. Domenici's determination to trim federal red ink runs counter to the wishes of right-wing senators who insist on no tax hikes. And as budget committee head he has sometimes had to step on senatorial toes.
Sen. James A. McClure of Idaho. The most obvious choice for the conservative wing of the GOP, Senator McClure is a founder of the Senate Steering Committee, an informal group of Republicans on the right. He has argued that his closeness to the Reagan White House would be a major benefit. In fact, an aide says that ''to a certain extent'' Senator McClure is running on President Reagan's coattails. However, the White House is scrupulously staying out of the contest, sending no signs about a favorite.
Affable and easygoing, McClure might be somewhat like majority leader Baker in style, although Baker set ideology aside in his leadership role. McClure will have to reach out to centrists, and in this he may be helped by his role as chairman of the GOP Senate Conference, which he has forged into a public relations organ for fellow Republicans.
As chairman of the Senate Energy and Natural Resources Committee, McClure has championed development over protection for federal lands in the West. But this year he helped complete a compromise federal wilderness law. He is a staunch friend of the gun lobby.
Sen. Ted Stevens of Alaska. In the line of succession, assistant majority leader Stevens is the apparent heir to Baker. Although he has held the No. 2 GOP Senate post since 1977, the Alaskan has been considered a dark horse for the top job, largely because of a hot temper. Senator Stevens also has conceded that his preoccupation with the parochial interests of his state might hurt his candidacy. But he nonetheless has campaigned hard on the basis that he has been a good soldier for the party and deserves promotion. He has taken some difficult positions for his fellow senators, pushing hard for pay raises and tax benefits for lawmakers.
Stevens is not strongly identified with political philosophy, although he is a conservative. He has proposed new rules for streamlining the Senate but would be unlikely to try to force new discipline on his colleagues.
Sen. Richard G. Lugar of Indiana. The logical ''compromise'' candidate could be this uncontroversial if somewhat bland conservative. An organization man, Senator Lugar headed the GOP's senatorial campaign this year. His noncombative style might be exactly what his GOP colleagues want in their new leader. He has not chaired a Senate legislative committee and has had few occasions to make enemies.
A solid conservative and Reagan backer, Lugar's greatest legislative achievement was a bill that would appear to run counter to his conservatism - the federal bailout of Chrysler Corporation. As of last week he did not have enough first ballot votes. He wrote his colleagues, ''I will need your early vote to remain an alternative in the final balloting.''
With so many factors involved, the outcome of the vote for majority leader is very unpredictable. For some senators it is a case of hoping to move into vacated committee chairmanships.
For example, the election of Senator Lugar would probably clear the way for Sen. Jesse Helms of North Carolina, an arch New Right leader, to become chairman of the Senate Foreign Relations Committee. If McClure is chosen, then Sen. Lowell P. Weicker of Connecticut takes over the Energy Committee. Some Westerners are not keen on that.
A Dole election would make Senator Packwood of Oregon the chairman of the Finance Committee, which might be disagreeable to the White House. Although a fiscal conservative, Packwood has fought the Reagan administration over civil rights issues.
One argument for Stevens is that his election would not disrupt committees, since he holds no major chairmanship. It may boil down to friendships. ''If your buddy is majority leader, then you can get on the phone'' and tell him about a problem, says a staff member.