The first time Howard County Executive J. Hugh Nichols ran for elective office was in 1966, when he won a seat to the last state convention held by the Maryland Democratic party.

That was also the year Spiro T. Agnew capitalized on a divisive four-way Democratic primary and beat George Mahoney for the governorship. Agnew's administration was the last time the GOP held the Maryland statehouse.

Almost 20 years later, as someone who is "very much a student of politics," Nichols believes that history might repeat itself. Which is why the 54-year-old county executive is almost certain to say "I do" to a marriage proposal from Maryland Republicans who are urging -- nay, begging -- him to switch parties.

Nichols, a Democrat of three decades' standing who is nearing the end of his second and last term in Howard, has been wooed for several months now by Republican officials who are desperately searching for a credible candidate to carry their party's standard in the 1986 election.

The seduction of Hugh Nichols -- being undertaken with promises of support, financial backing, and the kind of respect he never got from the press or Democratic bigwigs when he was running as a Democrat -- reached a fever pitch Monday. As Republican officials were presenting Nichols with a petition urging him to switch parties, signed by most of those who attended the Republican state convention in May, Vice President George Bush just happened to call.

Bush's call coincides with a national effort by the Republican Party to win converts among the ranks of Democrats. And it fell on receptive ears.

Though Nichols is playing the role of thoughtful statesman -- "I am evaluating the whole thing with deliberate speed; I'm mulling over the ideological and philosophical compatibilities," he says -- there seems an inevitability to the choreography.

It may be that a poll Nichols has commissioned will convince him that the Maryland electorate won't look with favor on a party-switcher. But the more likely scenario is a well-staged press conference in the next few weeks to announce that Nichols and the GOP have tied the knot.

And why not? Nichols, the first Democrat to declare his candidacy for governor officially, was almost totally spurned by his own party's leadership and the media, The Washington Post included. With heavyweight contenders such as House Speaker Benjamin L. Cardin, Baltimore Mayor William D. Schaefer and Attorney General Stephen H. Sachs expected in the race, no one paid any attention to Nichols. He dropped out in May.

Now, people are noticing him. As GOP Chairman Allan C. Levey said, the media are covering him "more than he was covered in the last seven years."

If nothing else, that says volumes about the plight of the Republican Party in Maryland. For despite having carried the state for Reagan last fall and increased signs that it is making inroads among young voters, the party still suffers from a woeful lack of candidates with statewide potential.

Only a few months ago, Levey and others in the GOP were talking about tapping a big-name businessman to run for governor because the best it had was a few capable, but reluctant legislators. Eastern Shore poultry producer Frank Perdue's name was one that came up.

But the heavy corporate type never materialized, exposing once again what Levey admits is a chronic problem: not having a farm club.

So, like George Steinbrenner, Levey went looking for free agents. And if Nichols isn't exactly Dave Winfield, circumstances could conceivably turn him into a slugger.

Levey believes Nichols is just the ticket to appeal to the yuppies and soon-to-be yuppies who are registering as Republicans and helping to erode, if slowly, the Democrats' 3-to-1 registration edge.

"He fits the mold," Levey said. "He's a fiscal conservative and a moderate on social issues. He's a mainstream Republican."

Though Nichols is not the sort to excite voters, he is likely to be a stronger campaigner and better candidate than the party's 1982 nominee, the somewhat erratic Bob Pascal. Nichols' campaign trademark, the nickel lapel pin, may be hokey, but it has a certain "cornpone panache," in the words of one Democrat.

But most important is the prospect of a real Democratic dog fight. If, as many expect, the Democratic contest evolves into a two-way race between Schaefer and Sachs, it is not likely to be a polite affair. It will be a nasty struggle between two wings of the party that detest each other.

"Someone is going to lose and someone is going to be bitter," said one Democratic insider. "Hugh may be the alternative. He will automatically inherit a lot of support."

In Maryland politics, stranger things have happened -- such as Agnew winning the governor's race as the liberal candidate.