MEXICO CITY (AP) — The ruling party of Mexico's President Andrés Manuel López Obrador won the governorship of the country's most populous state, dealing a life-threatening blow to the old ruling Institutional Revolutionary Part y — or PRI — which had governed the State of Mexico without interruption for nearly a century.

With over 99% of precincts counted in a preliminary report, electoral authorities said Monday that Morena's Delfina Gómez won 52.7% of votes in the State of Mexico — which surrounds Mexico City on three sides — to 44.3% for the PRI's Alejandra del Moral.

Del Moral later gave a concession speech acknowledging her defeat.

The result was a new low for the PRI, which held Mexico's presidency uninterrupted for 71 years until losing power in 2000 elections; the party had governed the State of Mexico and its 17 million inhabitants for 94 years until its loss Sunday.

The PRI managed to hold on to the governorship of the sparsely populated northern border state of Coahuila, and governs the neighboring state of Durango in coalition with other opposition parties. But the PRI is now a shadow of the old days when it ruled Mexico with a combination of hand-out programs and corruption.

PRI party leader Alejandro Moreno said Monday that speculation about the PRI's demise was wrong and that the party would survive, but as part of a broad opposition coalition of left, right and center groups that will seek to field an alliance candidate in the presidential elections a year from now.

“Elections are won with total votes across the country, not with governorships,” Moreno said, although state governments in Mexico historically have been a base to mobilize power and cash that can play a key role in federal elections.

Morena now governs 22 of Mexico’s 32 states, propelled by López Obrador's personal popularity — and more generous payments to the elderly and students than the PRI offered. The conservative National Action party governs five states, the Morena-allied Green party governs one and the small Citizens Movement holds two states.

López Obrador said he was pleased with the results, but struck a magnanimous tone Monday, saying his administration would deal fairly with governors from all parties.

“We have to serve all citizens, whatever party they belong to, that is our responsibility,” the president said.

Gómez celebrated her victory as the first woman to serve as governor in the State of Mexico.

“This is a victory for working families, this is a victory for us women, who have fought for years for the recognition of our rights,” Gómez said in a victory speech late Sunday. The state has been plagued by a bloody series of killings of women in recent years, and widespread poverty among female-headed households.

The State of Mexico covers everything from Mexico City suburbs, industrial sprawl and rural communities plagued by violence, and displays stunning extremes of inequality, violence and corruption.

The contest was closely watched, too, because of its potential implications for next year’s presidential elections. Even without having selected its nominee yet, Morena is considered the frontrunner in that national election and will be even more so with control of the State of Mexico.

Political scientist Georgina de la Fuente of the Tecnologico de Monterrey university noted that Sunday's results highlight several things: the PRI has been defeated, though perhaps not as soundly as expected; Morena is not invincible; and parties are going to have to reconfigure their agreements. She added that the smooth elections also confirmed the effectiveness of Mexico's electoral system, whose authorities had come under heavy fire from López Obrador.

The loss of the State of Mexico could spell the end of the PRI's political relevance on a national stage.

Turnout was only about half of eligible voters in the State of Mexico.

“It doesn't seem like the elections have excited” people, said Miguel Agustín López Moreno, a political scientist and social worker in Ecatepec, one of the state's largest municipalities. He was uncertain the situation for residents would change significantly, attributing the Morena party's success in large part to the amount of resources it invested in the state.

Adair Ortiz Herrera, a 21-year-old information systems student from Coyotepec, a rural area in the northern part of the state, said before the results were known Sunday that he was sure “a new direction” was coming. “My vote is to end the current government's hegemony,” he said.

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Romero reported from Naucalpan, Mexico. Emilio Lugo in Huehuetoca, Mexico, contributed to this report.