MESA, Ariz. — At first glance, it had the makings of a spirited election: the leader of Arizona’s crackdown on illegal immigration facing off at the polls with an immigrant from Mexico who believed that the state had gone too far.

But the immigrant, Olivia Cortes, a retiree who filed papers in July to challenge the State Senate president, Russell Pearce, disappeared from the political scene last week just as quickly as she had appeared. Ms. Cortes’s candidacy for a legislative district in this working-class community east of Phoenix, it now appears, had been a dirty trick.

Critics of Mr. Pearce’s hard-line approach to illegal immigration collected enough signatures to force him into a recall election in November. But allies of Mr. Pearce, who is one of the state’s most powerful politicians, did not take that humiliation lightly. They recruited Ms. Cortes in what was an effort to split the anti-Pearce vote, particularly among Latinos, a judge later found.

Greg Western, a Pearce ally who is the chairman of the East Valley Tea Party, was a central figure in the scheme and became Ms. Cortes’s campaign adviser. Soon, signs promoting Ms. Cortes’s candidacy appeared on street corners, bearing the motto made famous by Cesar Chavez of the United Farm Workers: “Sí, Se Puede!”