espite serving as secretary of education in George Bush's Cabinet, Lamar Alexander was able to present himself legitimately as a Washington outsider in the 1996 presidential race because the core of his experience was in Tennessee. He had been a two-term governor, president of the University of Tennessee, and a successful businessman. Alexander ended up battling two others - publisher Steve Forbes and TV personality Pat Buchanan - for the outsider track, but the nomination went to the consummate insider, Bob Dole.

Now the Republican Party is headed toward the nomination of a candidate with minimal electoral experience.

Alexander's eight years as governor represent three more years in elective office than those held by the top five finishers in Saturday's Iowa straw poll combined. George W. Bush has been governor of Texas for less than five years. Forbes, Elizabeth Dole, Gary Bauer, and Buchanan are not encumbered by any political victories at all.

Alexander ended his candidacy yesterday with a statement notable for its graciousness and brevity. The Republican campaign is diminished.

Perhaps Bush will earn the GOP nomination. Attorney Tom Rath of Concord, N.H., Alexander's leading supporter in the Granite State, said yesterday that Bush ''hasn't made a mistake yet.'' But he added that the time to judge people is when things aren't going well, and, with Bush, ''that's what we don't know yet.''

The comment is on target. Because of his massive spending - challenged only by Forbes - combined with a very early primary calendar, Bush may be able to secure the nomination in the first few months of next year. But no Republican president since Eisenhower has won on his first attempt. What happens if problems develop in Bush's candidacy?

Alexander should have been able to offer one answer. A system that spits out a candidate of his caliber six months before the first convention delegates are chosen threatens to limit the choices left to most voters in a most troubling manner.