The reality of the Republican presidential race is that there is Ronald Reagan, and then there is everyone else. Reagan may suddenly develop chronic laryngitis, the gout, falling hair or moldy metaphors. But unless one of these dread afflictions strikes, there is no obvious reason why this most durable and skillful of campaigners should fail to win the prize he has so long and eagerly sought.

Still, fail he did in 1968 and 1976, and the hope beats in at least six Republicans breasts that the third time may not be the charm Reagan supposes.

So on the off-chance that Republicans may need a new face in 1980, the "everyone elses" are parading themselves in all their glory, while Reagan dallies in the delightful indolence of the front-runner.

The most mysteriously anonymous of that pack turned up in Washington last week to occupy the platform the National Press Club has generously been providing the GOP pretenders. George Bush came to town, trailing the question of how a man with such impressive experience and leadership support can be as much an unknown to the voters as Bush apparently is.

Boasting a rich campaign bankroll, good looks, a string of major jobs, a flock of endorsements, and an organization that may be the most potent threat to Reagan's in several key states, Bush has noneless managed to work himself down toward the bottom of the GOP preference polls.

His admirers say that marks him as the Jimmy Carter of 1980 -- the guy who will come from nowhere because of assets no one seemed to notice until he began to win. His detractors say he is more like Birch Bayh, a presidential candidate with marvelous paper credentials, which unfortunately proved to be just that.

It seems strange to talk of Bush as a mystery figure in Washington, where he served with some distinction as a congressman, a party chairman and as director of the Central Intelligence Agency, and where his skills as ambassador to the United Nations and envoy to China are well-known.

But, like Carter in the months leading up to the 1976 primaries, Bush has deliberately skirted the capital, while building his organization in Iowa, New Hampshire and the other early delegate-selection states.

Thus, his speech at the press club was a bit of a revelation to reporters and politicians who thought they knew him well. It was rather better than anyone expected.

It was a solid and serious discussion of the economic and military challenges awaiting this country in the 1980s. The speech deviated little from the standard Republican rhetoric, but showed that Bush has been doing his homework on the issues.

The delivery drew more comment than the substance, however, for it suggested that Bush has learned some useful techniques in his months on the civic-club circuit. He is still no threat to Reagan or John Connally as an orator, but he delivers his words now with conviction and authority, rather than the ingratiating but somewhat irresolute tone he previously employed.

His wife has won her argument against the half-glasses he liked to wear, and the new full lenses seem to complement the full voice. The suggestions of a speech coach who has been critiquing his performances appear to have improved the rhythm and intonation of his address.

These seemingly petty matters are not petty in Bush's case, because it is only the public presence that has been lacking to make him a serious figure in the Republican field.

His initial struggle for survival is with the other "centrists" in the race, particularly Sens. Howard Baker Jr. (R-Tenn.) and Bob Dole (R-Kan.).At this point, he is miles ahead of both of them in money and organization, but way behind in public recognition and support.

In the next three months, the Bush campaign will push for that public recognition, moving from the living rooms where he has been spending his time to larger forums, and also buying advertising in the early battleground states.

Iowa is his best chance to score a Carter-like breakthrough, and he has mobilized broader support of party leaders there than anyone except Reagan.

In a Reagan-less world, his chances might look pretty good. Whether any large number of Republicans will really look beyond Reagan is another question.