MEXICO CITY - Voters sent President Vicente Fox a strong message Sunday, denying him his coveted majority in the 500-seat lower house of Congress and giving more control to the political party he ousted from the presidential mansion three years ago.

Results of the nationwide midterm elections were viewed as a referendum on the first half of Fox's single term in office, and a quick count conducted by the Federal Elections Institute showed that the Institutional Revolutionary Party will control 222 to 227 seats in the Chamber of Deputies.

A reinvigorated PRI means Fox will have to hurry to build connections with Congress if he is to have any hope of passing initiatives that have become his most pressing goals: fiscal, labor and energy reform. Perhaps more important, it means the 2006 presidential elections are wide open and Fox's National Action Party (PAN) has no guarantee of repeating its stunning 2000 win.

The election, coming at the midpoint of Fox's presidency, became a rejection of the change promised when Fox reached the presidency, ending 71 years of one-party rule by the PRI, which was marked by rampant corruption and authoritarianism.

"This is a mandate for dialogue, restraint and building agreements," Fox said in a televised address Sunday. "Now comes the time for working together," he said, acknowledging that Mexicans want him to work more with Congress.

"People really are upset with the PAN," political analyst Jorge Chabat said. "Fox didn't do anything. He didn't put anyone in jail, he didn't come up with any agreements. I hope the PAN will react after this."

Violence by voters

Some of the upset showed in fistfights and burnt voting booths that kept elections from proceeding in San Salvador Atenco, in Mexico state, and in Chiapas state, both places where Fox's efforts have failed spectacularly. In Atenco, angry residents last year defeated Fox's plans to build an airport on commonly owned land. In Chiapas, indigenous people led by the Zapatista Army of National Liberation remain angry over an indigenous bill of rights that became law despite what they viewed as serious weaknesses.

In all, 80 of more than 121,000 voting booths, less than 1 percent, did not work or could not be set up because of the violence, according to the Federal Elections Institute.

The institute's quick count of unofficial results showed the PRI got 34.4 percent of the vote and PAN 30.5 percent, slightly less than percentages predicted in pre-election polls. PAN likely will hold 148 to 158 seats in the lower chamber.

The Democratic Revolutionary Party received 17.1 percent of the vote, staying within performance forecasts and earning 93-100 seats, the elections institute said.

The results largely agreed with election day polls.

An exit poll by the newspaper Reforma showed the PRI with 37.5 percent of the vote in the congressional races, while PAN held 31 percent and the left-leaning Democratic Revolutionary Party, Mexico's third major party, had 18 percent.

As it did in congressional sessions in the past three years, the PRD will have the chance to play the spoiler for Fox's initiatives if it chooses to ally itself with the PRI. Alliances with PAN are less likely, though not impossible.

Fox has an ace in Elba Esther Gordillo, the PRI secretary who is assured a seat in the lower chamber and is most likely to lead the party in the Congress. A longtime friend of Fox and of his former foreign secretary, Jorge Castañeda, Gordillo has been described by analysts at Merrill Lynch as the person who will provide a bridge for Fox to achieve at least some wins in Congress.

For example, though Gordillo has kept her views close to the vest on the controversial topic of energy privatization, party President Roberto Madrazo Pintado is open to the possibility. She likely will follow the party's line.

On Sunday as voters went to the polls, Gordillo kept things diplomatic.

"Our responsibility of tomorrow is for the PRI to seek consensus, to give direction to actions (of the Congress)," Gordillo said as she emerged from the voting booth in Mexico City. "This consensus will be to seek everything that, through the legislative route from the legislative branch means governing with responsibility, with commitment to Mexico and Mexicans."

The balance of the vote percentage in Sunday's elections went to the Green Party, with 6.2 percent; the Workers' Party, with 2.4 percent, and the newly formed Convergencia Democratica, with 2.3 percent. Other small parties did not gain enough votes to retain their federal registration.

Turnout low at polls

Voters trickled into polling places in a steady but thin stream, and officials at two polling places estimated turnout at about 40 percent.

"It's disastrous," said Agustin Romero, who trekked from his new home on the outskirts of town to vote for the PRD in the central neighborhood of La Condesa because of a recent move. "It looks like they don't think the people have a memory. Now the PRI wants to save us and the PAN believes it's the master of the country when during more than 60 years it wasn't even a real opposition."

Withholding judgment

Belen Gomez, voting in La Condesa, said it's too soon to pass judgment on PAN.

"I think they have to be given an opportunity," she said. "Let's see if they get a majority and if they do what they can."

Some who took time to go to the polls said that, beyond any disillusion with campaigns and promises, they consider it their duty to vote.

Antonio Salas Contreras, a 64-year-old amputee in a wheelchair at a polling place in the working-class Doctores neighborhood, made his way to the booth though he had little sense of the candidates.

"Well, it's my obligation," he said. "With my years, I have been in many elections in which one doesn't specifically go for a candidate. Why? Because one doesn't know him."

Salas Contreras said he voted for the PRD, the party of Mexico City Mayor Andres Manuel Lopez Obrador, who has garnered unprecedented support through visible public works projects like a giant loop overpass to relieve traffic and aid programs for the elderly.

With three years before the next presidential bout, Lopez Obrador, the PRD's likely entry, appears to be the strongest politician in Mexico.

Voting in his home state of Tabasco, Madrazo Pintado said he felt good about the PRI's performance in this election.

"All the polls are indicating that the PRI will be the party with the greatest number of deputies," he said. "We are very optimistic about the chance of obtaining this majority, and we are very happy that it might happen this way."