MEXICO CITY — It was an old-style landslide for the Institutional Revolutionary Party, which used to rule Mexico from top to bottom.
The party's hopes for once again ruling Mexico soared Monday after official tallies confirmed a sweeping nationwide victory in midterm elections a day earlier.
In addition to a win in Congress, the party, known as the PRI, held leads in five of six governorships, including two in states that had seemed securely under the control of the conservative party of Mexican President Felipe Calderon.
"The PRI Crushes the President," blared the daily Milenio newspaper.
The PRI came up short on an outright majority in the lower house of Congress, known as the Chamber of Deputies. But it should be able to command the legislative agenda by joining hands with smaller parties.
The big loser was Calderon's National Action Party, which was hurt by the economic slowdown and a relatively low turnout that favored the PRI's seasoned get-out-the-vote machine.
The outcome will make it harder for Calderon to steer his legislative agenda, which includes proposed tax reforms and crime-fighting laws, during his three remaining years as president. The PAN has the most seats in the Senate, but not a majority.
During the campaign, the PAN sought to keep the spotlight off the country's economic troubles by emphasizing Calderon's 2 1/2 -year-old crackdown on drug traffickers.
But fretful voters sought reassurance in the PRI, which played up its long governing experience while repackaging itself as a modern party that had shed a corrupt and authoritarian past.
The PRI ruled for 70 years before losing to Calderon's party in 2000. It won a majority in the Chamber of Deputies three years later in results similar to Sunday's, but succumbed to infighting and finished a dismal third in the presidential vote in 2006.
The PRI beat the PAN by nearly 9 percentage points -- 36.6% to 28% -- in Sunday's congressional race, according to the government's preliminary tally. It led in gubernatorial races in two conservative states -- San Luis Potosi and Queretaro -- that everyone assumed were solidly in the PAN fold.
In the Pacific state of Colima, the PRI candidate for governor, Mario Anguiano, won despite allegations by opponents that he was linked to the drug trade. Anguiano, whose brother and cousin are jailed on drug charges, denied any ties.
The PAN had one unexpected win: for governor in the northern state of Sonora, a PRI stronghold. It was probably helped by public anger toward state officials over a June 5 fire at a day-care center that killed 48 children in Hermosillo, the capital.
Overall, results appeared to reflect public disenchantment with the country's political direction. More than half of the 78 million registered voters stayed home. One in 20 ballots were deemed invalid, a sign that a protest campaign had succeeded in persuading many unhappy voters to deface their ballots. In Mexico City, the rate of null votes was more than one in 10.
Many Mexicans say they want better jobs and solutions to the burgeoning crime rate, poor schools and outdated hospitals.
"They have given the PAN nine years to do it and they don't think the PAN has done it," said George W. Grayson, a Mexico scholar at the College of William & Mary in Williamsburg, Va., who was in Mexico City for the voting.
The PRI also appeared to profit from bitter feuding within the main leftist party, the Democratic Revolution Party, or PRD.
The PRD, which finished closely behind Calderon three years ago, managed a meager 12% this time.
It remains to be seen what the PRI does with its newfound clout.
"What the PRI was asking for was, 'Give us a shot.' That's not a mandate," said Daniel Lund, a pollster and political analyst based in Mexico City.
Mexico's leaders face daunting problems, including declining oil production, persistent crime and a recession that has hammered tax receipts and is expected to shrink the economy by more than 5% this year.
Commentators said the rival parties will have to cooperate to get laws passed.