MEXICO CITY — A cussing rancher known as El Bronco, who made Mexico’s first serious run for governor as an independent candidate, handily defeated his competition on Sunday, according to exit polls, in a race closely watched as a sign of voter frustration with entrenched, established parties they see as ineffectual and corrupt.
The candidate, Jaime Rodríguez Calderón, running for governor of Nuevo León State, an economically vital business and industrial hub near the Texas border, bested his rivals by at least six percentage points, according to the polls.
“Nuevo León will be the start of a second Mexican revolution,” he said in a brief telephone interview not long after the exit poll results were announced and as he awaited preliminary official results expected sometime Monday morning.
“It’s a sign that you can have a revolution at the polls. We are giving the parties that had been governing a six-year vacation,” he added, referring to the term of the governor’s post.
Local news outlets reported that hundreds of his supporters, egged on by social media, had swarmed a plaza to celebrate, while his closest rival admitted that the race was close but did not concede.
Mr. Rodríguez, the former mayor of a farming suburb of Monterrey, drew attention for his blunt, profane speeches; claims about taking on drug gangs; and a campaign that largely took off through social media, appealing particularly to the young. He cultivated a maverick persona, wearing boots and at some events riding a horse.
His platform was short on details on how he would govern, beyond promises that it would be differently than the Institutional Revolutionary Party, known as the PRI, which has long dominated politics there.
He is a former, 30-year member of party, raising skepticism from critics that he could really operate independently of it, but he had renounced it and campaigned heavily against it.
Still, a range of analysts said his candidacy would rattle traditional parties and could raise the prospect of a viable independent candidate in the next presidential election, in 2018. (Mr. Rodríguez has sought to play down speculation that he might run then.)
“The triumph of El Bronco is a warning to the parties, renovate or die, and the presage of a citizen candidate in 2018,” Enrique Krauze, one of Mexico’s most highly regarded political historians, said on Twitter.
Across Mexico, polls have shown voters’ regard for the three main parties at a low point. In the election on Sunday, in which 500 seats in the lower house of Congress were contested as well as nine of 31 governor’s posts and hundreds of municipal and state offices, the electorate seemed neither inclined to heavily punish the PRI nor to reward opposition parties many find just as contemptible.
The PRI, with its allied parties, retained a majority in the lower house of Congress, according to preliminary official results. That came despite the party’s standard-bearer, President Enrique Peña Nieto, weathering recent conflict-of-interest scandals over home purchases by his wife and a cabinet minister through a government contractor, as well as anxiety over a wave of violence.
Smaller parties made gains as well in Congress, pointing to an increasingly fragmented political landscape in which the traditional parties may find their power diluted.
Mr. Peña Nieto has already pushed through the more ambitious pieces of his agenda, including a revamping of energy legislation that opens the door to foreign participation in the notoriously closed, state-run oil industry and an overhauling of telecommunications law to stimulate more competition and lower prices.
But Mexicans have complained they have yet to feel the changes in their pocketbooks. The economic growth has slowed, and violence again dominates headlines, including 16 people killed on Saturday in a confrontation among citizen patrol groups in rural Guerrero State.
Still, rather than a referendum on Mr. Peña Nieto, many analysts saw the outcome as a testament to the weakness of the opposition parties, which are splintered and have endured internal leadership fights.
The incumbent party also has lost ground in the three previous midterm elections, Andrew Selee, a Mexico scholar at the Woodrow Wilson Center in Washington, said in an analytical note on the election. “This election is hardly a repudiation of Peña Nieto’s government, but it’s certainly not a ringing endorsement, either,” he said.
The election unfolded in a tense atmosphere, as violence, particularly in long-restive southern states, has swelled in recent weeks. A number of campaigns complained about giveaways and vote buying, par for the course in Mexico.
Protesters burned ballots at polling sites in some locations on Sunday in southern Mexico and clashed with the authorities to disrupt the vote, including in Tixtla, in Guerrero State, near a rural teaching school attended by 43 students who disappeared and were believed to have been killed by a drug gang last fall in a case that rocked the nation.
But for the most part the vote was peaceful and sound, despite “isolated incidents,” an observer mission from the Organization of American States said in a statement.