IN MICHIGAN it is not quite spring yet, but politically, for the Republicans, it's almost 1988. In every other state the voters don't begin selecting national convention delegates for almost two years. But Michigan Republicans will start next month. Under an old state law that was abandoned for a time when the Democrats changed their rules but which has been revived now for the Republicans, Michigan's national convention delegates are chosen by state convention delegates who are in turn chosen, in January 1988, by the precinct delegates elected in the August 1986 primary. The filing deadline for getting on the ballot as a candidate for precinct delegate is May 27.

So in the next six weeks several thousand Michigan Republicans will be walking around the state's 6,000 precincts, getting the 15 to 20 signatures they need to get on the ballot. Assisting them will be boosters of various Republican presidential candidates. But not, you will be assured, actual campaigns themselves. A PAC called Fund for America's Future is expected to spend several hundred thousand dollars encouraging Republicans to run for precinct delegate, as a "party building effort"; FFAF's founder and honorary chairman is George Bush. The Michigan Opportunity Society headed by Detroit lawyer W. Clark Durant III will be spending at least $100,000 on similar party-building work; Mr. Durant is an unabashed supporter of Jack Kemp. Then there's the Freedom Council, an educational charity that is spending some $35,000 a month encouraging people from "the Christian community" to run as precinct delegates; the Freedom Council has sponsored three Michigan visits by Pat Robertson.

You get the idea. Three politicians who won't admit they are presidential candidates are sponsoring three committees that won't admit they are presidential campaigns to compete in a contest they won't admit is the beginning of the presidential race. In the process they avoid the limits of the federal campaign finance laws. Mr. Bush's FFAF has persuaded a 4-2 majority of the Federal Election Commission that its activities in Michigan are entirely directed toward "party-building" and not toward the presidential contest. Mr. Kemp's MOS claims it's only a state committee, not involved in federal elections. The Freedom Council says it is an educational charity, not involved in party politics. If you want to believe three impossible things before breakfast, there they are.

In the old days most states chose their party delegates early and watched as presidential candidates entered the race late. Now all but Michigan choose delegates long after candidates begin running. The hardest part of this horse-and-buggy politics in the automobile state will be keeping score: some precincts elect more than one delegate and some don't; candidates will be coy about saying which are their precinct delegates and which aren't; and commitments made in May or August 1986 can't be enforced in January or August 1988 anyway. But, whether you like it or not, 1988 has begun, at least in the precincts of Michigan.