Michigan supporters of Vice President Bush's presidential campaign said yesterday they are considering a legislative end run around the state Republican Party in their drive to deliver a majority of Michigan's 77 GOP convention delegates to Bush.

State Senate President John Engler said "we are looking at the option" of trying to enact legislation that would effectively overrule a delegate-seating decision this month by the Michigan GOP state central committee. That decision, engineered by the forces of Marion G. (Pat) Robertson and Rep. Jack Kemp (R-N.Y.), who control the party apparatus, threatened Bush's chances of winning a majority of delegates.

Marc Nuttle, manager of the Robertson's presidential bid, sharply criticized Engler's comments. "It's wholly unfair. That's really abusive . . . I would hope they {the Bush forces} keep it within the party."

Michigan will be the first state to select convention delegates. They will be picked at a state GOP gathering in Grand Rapids Jan. 29-30 by 9,000 "precinct delegates" elected in the August 1986 primary.

At issue, however, is the Bush campaign's contention that the 1,200 nominees to city and state offices selected last year should automatically become precinct delegates. The party nominees are believed to favor Bush. Adding them to the precinct delegates would improve his chances of controling the state's delegation to the national convention.

Engler said he expects to make up his mind on the legislative maneuver to overrule the party this week. Bush forces also are organizing a suit challenging the party decision.