AGUASCALIENTES, Mexico (CNN) -- Exit polls show Mexico's ruling party winning two out of three state governorships up for grabs Sunday, with the other race going to its center-right opposition.

Polls by both Televisa and Television Azteca showed candidates of the Institutional Revolutionary Party, or PRI, winning as expected in Veracruz, on the Gulf of Mexico coast, and Oaxaca, in the south.

But in central Aguascalientes state, exit polls showed that Felipe Gonzalez Gonzalez of the National Action Party, or PAN, would beat the PRI's Hector Hugo Olivares Ventura. However, PRI officials disputed that, saying their own polls show Olivares beating Gonzalez by 4 percentage points.

Going into Sunday's ballot, the PRI, which has dominated Mexican politics for seven decades, held all three of the governorships. But though it faces the prospect of losing Aguascalientes, Sunday's results were still something of a comeback for the PRI after a election disaster last year in which the party lost its majority in the lower house of Mexico's Congress.

Last month, PRI wrested the governorship of northern Chihuahua state away from PAN.

In Veracruz, the PRI's Miguel Aleman, a wealthy businessman and the son of a former president, took 52 percent of the vote, according to Televisa. Luis Pazos of PAN came in second with 28 percent. TV Azteca's projections showed the race to be somewhat tighter but also gave Aleman a substantial lead.

While the win was expected, political observers were looking at the strength of Aleman's showing because he is considered to be a possible contender for the presidency in 2000. Veracruz, with 4 million voters, is the third-largest state and could be crucial in the presidential ballot.

In Oaxaca, Televisa projected that PRI candidate Jose Nelson Murat Casab would take 51 percent of the vote, with Hector Sanchez, of the center-left Party of the Democratic Revolution, or PRD, finishing second with 34 percent. TV Azteca was projecting the same order of finish but with only a 6 point gap.