Arizona's secretary of state certified Monday that the state's beleaguered governor, Evan Mecham, must face a recall election this spring, setting up a political contest that is likely to feature a dozen candidates and split the Republican Party down the middle.

With formal notification that enough Arizonans have signed petitions to force the recall, the governor has the choice of resigning by Sunday or competing in a recall election -- officially nonpartisan but already the focus of intense political maneuvering. Mecham's office said Monday he will not resign. If he doesn't, the election will probably be May 17.

A recall election would essentially be a new gubernatorial election; whoever wins the most votes becomes governor. It takes only 3,300 signatures to get on the recall ballot. There will probably be three chief contenders: Mecham, a conservative Republican; Carolyn Warner, the Democrat whom Mecham squeaked by in the tight three-way 1986 gubernatorial election; and some senior Republican figure who is likely to be supported by most of the state's GOP establishment.

It is not completely certain who will emerge as the anti-Mecham Republican, but a corps of business and political leaders is promoting John Rhodes, former minority leader of the U.S. House. The 71-year-old Rhodes initially rejected pleas that he enter the recall election. But as pressure on him has increased, he has sounded more and more like a candidate.

It's not clear whether Mecham will still be in office next May, when the recall election is to be held. He faces a trial this spring on state felony charges. And an impeachment hearing is going on now in the state House. The major charges in both proceedings involve a campaign loan that Mecham failed to disclose in the 1986 campaign.

Conviction on the criminal charges would remove Mecham from office. Or, if the state House impeaches him, the state Senate could vote to oust him. Secretary of State Rose Mofford, a Democrat, would become governor if Mecham is forced out. Arizona has no lieutenant governor.

But the recall election, now that it has been certified, must go forward even if Mecham is out of office, according to a ruling last week by the state attorney general. In that case, Mecham would be likely to petition his way onto the ballot, if there is time. Rhodes or some other Republican with the blessing of the party leaders would probably run. And Warner has said she will run in the election even if her fellow Democrat, Mofford, is the governor by then. The name of whomever is governor will automatically be on the ballot.