AGUASCALIENTES, Mexico (AP) _ In what would be a crucial victory ahead of the 2000 presidential elections, the opposition National Action Party captured the governor's seat in the central state of Aguascalientes, according to television exit polls.

The ruling Institutional Revolutionary Party, however, said its own polls showed it was hanging on to Aguascalientes by 4 percentage points.

The polls by Televisa and Television Azteca also showed the governing Institutional Revolutionary Party, as expected, holding onto governors in the gulf coast state of Veracruz and the southeastern state of Oaxaca.

Official preliminary results were to be released later.

The vote in Aguascalientes came a month after National Action, known by its Spanish initials as the PAN, lost one of its six governor's seats. It was defeated by the governing party, known as the PRI, in Chihuahua. Aguascalientes was seen as the PAN's best opportunity to compensate for the loss.

According to Televisa's poll, PAN candidate Felipe Gonzalez Gonzalez captured 50 percent of the vote. The PRI's candidate, Hector Hugo Olivares Ventura, had 41 percent and Alfonso Bernal Sahagun of the center-left Democratic Revolution Party had 6 percent. It did not give the margin of error in its poll.

The business-oriented National Action has gained strength in Aguascalientes as the small, relatively prosperous state has become more urban and middle class in recent years.

Martin Diaz de la Vega, 32, a street salesman, said he voted for the PAN for the first time because he believes the PRI is corrupt.

``We need a change. Even if it's bad, I don't think it can be any worse,'' he said.

Turnout figures among Aguascalientes' 500,000 registered voters were not immediately available, but the state electoral council reported earlier in the day that turnout was strong and there were no major problems.

In Veracruz, Miguel Aleman, a wealthy businessman and the son of a former president, won with 52 percent of the vote, according to the Televisa poll. Luis Pazos of the PAN finished a distant second with 28 percent of the vote.

Veracruz, a party stronghold, was seen as essential for the PRI. With its 4 million voters, Veracruz has the nation's third-largest electorate and could be crucial in the presidential election.

If the final results reflect the showing of the exit poll, the win could make Aleman a top contender for the PRI's presidential nomination.

The PRI, which long maintained its power through a mix of patronage, strong-arm tactics and cheating at the ballot box, has seen devastating electoral losses in recent years following reforms aimed at cleaning up the vote and making elections more competitive.

The PRI suffered its worst setbacks last year when it lost control of the lower house of Congress and was defeated in the Mexico City mayoral race. But its won two of three elections last month, including the defeat of the PAN in Chihuahua.

In Oaxaca, PRI candidate Jose Nelson Murat Casab won with 51 percent of the vote, according to the Televisa exit poll. It said the Democratic Revolution candidate, Hector Sanchez, finished second with 34 percent.

However, an electoral dispute appeared to be shaping up in Oaxaca, where both the PRI and Democratic Revolution insisted that their own polls showed each of them ahead.

Another exit poll, conducted by the Arturo Rosenbluth Foundation, said its survey showed Democratic Revolution winning the Oaxaca governorship with 38.1 percent of the vote, following by the PRI with 36.9 percent and National Action with 17.8 percent.

The foundation said in a written statement that the exit poll was conducted at 137 of 3,685 polling places in Oaxaca and that it had a margin of error of 0.064 percent.

Representatives of several political parties complained to electoral authorities that foundation workers conducting the survey had entered polling booths and in some cases appeared to be trying to influence the way people voted.

Foundation spokesman Daniel Ponce denied the accusations.