TLAXIACO, Mexico  Gabino Cué is running for governor of Oaxaca State as the candidate for so many parties that his campaign is handing out a pamphlet explaining how to mark the ballot.

In simple cartoons, the drawings promise voters that Mr. Cué will kick out the party that has governed Oaxaca for 80 years and clean up the state.

A decade ago, Mexico ended more than 70 years of control by the Institutional Revolutionary Party and elected an opposition president. But in Oaxaca, the PRI, as the party is known, has held fast through a vast party machine that dispenses patronage and often seems accountable to no one except the governor.

The other parties believe that the only way to dislodge the PRI here is to unite across ideological lines against it. Mr. Cué is the candidate for a coalition of the conservative National Action Party and the leftist Party of the Democratic Revolution, along with a couple of small parties.