Colorado Republicans are in disarray and lack a clear frontrunner in today's four-way primary to select a nominee to oppose Sen. Gary Hart (D-Colo.).

The race features a bona fide national figure in former Army secretary Howard H. (Bo) Callaway, a former congressman from Georgia living in Crested Butte, where he owns a ski resort.

Also running for the Republican nomination are lawyer John Cogswell of Englewood, a political newcomer; state Sen. Sam Zakhem of Denver, who has staked out the far right, and Secretary of State Mary Estill Buchanan of Boulder, a moderate.

Callaway, 53, raised twice as much money as any of his three rivals, about $330,000 plus $112,000 which he loaned his campaign.

Polished and experienced on the campaign trail, Callaway says he possesses the savvy to defeat a tough incumbent like Hart. But his southern-style effusiveness turns off many Republicans accustomed to a more low-key Colorado approach.

Some GOP leaders worry that controversies in Callaway's past would hurt his general election campaign if he is the nominee. He was forced to step down as President Ford's campaign manager four years ago when the Sen. Floyd Haskell (D-Colo.) claimed Callaway used his influence as Army secretary to gain favorable treatment for his Colorado ski resort. Congress and the Justice Department investigated and no wrongdoing was proven.

Callaway's polls suggest that he will win a close victory over Buchanan today, with the other two competitiors far behind. But undecided Republicans number about 20 percent, according to those polls.

Callaway says, "It's all going just right and that just turns me on. There's no part of me that says, 'relax' when things are going good. Right now everything is falling into place."

Buchanan, 45, has been secretary of state for six years, and won reelection in 1978 by the highest majority of any Republican running in Colorado.

She stresses conservative issues, but many GOP activists say she is not conservative enough. She has rankled some party members with her active support of the Equal Rights Amendment and federally financed abortions for the poor.

In recent weeks, Buchanan dominated news coverage of the race with her strategy for qualifying for the primary.

She failed to win a place on the ballot at the Republican state convention June 7, and turned to the alternate route -- petitioning her way onto the ballot.

After weeks of legal battles that generated publicity, the Colorado Supreme Court ruled that Buchanan would be on the ballot.

Asked if her campaign to make the ballot would generate a sympathy vote, she said, "I wouldn't call it a sympathy vote. I would call it a vote of pride. The basic line we hear wherever we go is, 'Give 'em hell, Mary.'"

Buchanan may have hurt herself over the weekend, however, when she told an audience that Democrats were eligible to vote in Tuesday's primary. They are not, and her opponents have taken delight in pointing out that the secretary of state doesn't even understand the voting laws she oversees.

Cogswell, 41, is running as a "non-politician" without a record.

Zakhem, 42, is a hardline conservative and devout Christian who has a loyal following across the state, especially in rural areas.

Hart is unopposed for renomination by the Democrats.