IN a bellwether state where Mexicans first took arms against colonial rule, voters may give a strong rebuke to the nation's ruling party this month for the country's economic crisis.
If this electoral uprising against the Institutional Revolutionary Party (PRI) comes to pass, the beneficiary at the May 28 ballot here would be a blunt-talking gubernatorial candidate from the conservative National Action Party (PAN).
Two independent polls show PAN contender Vicente Fox Quesada defeating his PRI opponent, Ignacio Vazquez Torres, by a margin of roughly 2-to-1.
That is an astonishing turnaround from presidential and municipal elections last year, in which the PRI trounced the PAN here with ease.
Should Mr. Fox prevail, analysts say he will be well-positioned to run for the presidency in the year 2000.
''Fox would test the PRI government far more than others of his party. He represents a more combative faction,'' says Rafael Jimenez, chief pollster for the Mexico City daily Reforma, whose surveys have shown the PAN candidate in a commanding lead.
The Mexican political landscape has shifted dramatically since a sharp devaluation of the peso in late December plunged the country's economy into deep recession. President Ernesto Zedillo Ponce de Leon has seen the fortunes of his party, the PRI, sink along with the peso. The conservative PAN, touting a pro-business and antitax agenda, has seized the opportunity far more effectively than the splintered left-wing opposition.
''The popular anger at the economic crisis is fundamental,'' says Luis Miguel Rionda, a political scientist at the University of Guanajuato. ''In 1994 we saw the opposite reaction because the economic situation in Guanajuato was stable. But those illusions disappeared in December.''
Voters in the important urban state of Jalisco earlier this year ousted the PRI from the governorship and installed the PAN. And in the southeastern state of Yucatan, the PAN is mounting a strong challenge to the PRI in another May 28 gubernatorial election.
BUT the PAN has made its strongest inroads in Guanajuato. This central Mexico state, with a population of more than 4 million, is a microcosm of the country, with its fast-growing industrial cities, cobblestoned colonial towns, and broad belts of rural countryside.
Fox, an ex-congressman and former president of Coca-Cola's operations in Mexico and Central America, cuts a confident, populist figure on the campaign trail. At a recent candidate forum in the Guanajuato convention center, he wore his trademark cowboy boots, ''FOX'' brass belt buckle, and a buttoned-down shirt open at the collar.
While other suit-and-tie candidates fidgeted, Fox flashed an easygoing ''V'' for victory sign. In his speech, he vowed to make Guanajuato state a better place for business and argued that the PRI model of centralized government must give way to local control.
''The political task of the moment is to dismantle corruption, at all levels of government, so society can grow,'' he added.
In the 1991 gubernatorial election here, Fox lost to a PRI candidate whose victory was so tainted by charges of fraud that another PAN politician was appointed to rule until new elections could be held.
Meanwhile, Mr. Vazquez Torres, a federal senator and scion of a local ruling family, is running sluggishly against Fox with old-style PRI tactics. In a campaign stop in Salamanca, workers from a pro-PRI union were bused in to fill a meeting hall where the candidate listed his promises to aid the town, accompanied by a slide show. They applauded perfunctorily.