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Argentina's ailing President Cristina Fernandez is now lame-duck leader with no clear successor, confronting economic storms and new rivals who are aiming to lure away the allies that give her Front for Victory just enough votes to control Congress.

Sunday's congressional vote demolished any chance for her to seek re-election by amending the constitution, and opponents already are maneuvering for a chance to replace her in the 2015 presidential vote, ending a decade-long political era dominated by Fernandez and her late husband, Nestor Kirchner.

Former Cabinet chief Sergio Massa was the big winner in the mid-term elections. He broke with Fernandez just before this year's campaigns and trounced the candidate she hand-picked to lead her slate for the Chamber of Deputies from the province of Buenos Aires, which is key to winning any presidential election.

While Massa's new Renewal Front won only 19 of the 257 seats in the lower house, he and other opponents will be able to deny the government the majority it needs to pass laws if they can persuade just a few more Fernandez loyalists in each chamber to switch sides. Only months ago, Fernandez's loyalists dreamed of the two-thirds majority needed to change the constitution.

"We're going to work with all those leaders who want to be part of the construction of the future," Massa said Monday as he and other politicians analyzed the results in radio and TV interviews.

While Fernandez still controls Congress, the ruling party and its allies got just 33 percent of the vote nationwide against a fractured opposition.

Since half of the Chamber of Deputies and a third of the Senate were up for grabs Sunday, that means the government can probably count on 132 votes in the lower chamber, four more than the all-important majority it needs to dominate the agenda. Provisional results suggest it may have 38 votes in the Senate, where the magic number is 37.

Analysts aren't sure how she'll respond. Reach out and build consensus to confront Argentina's challenges, or intensify her heavy-handed style of governing?

"There are two possible scenarios after these elections," Ignacio Fidanza, director of lapoliticaonline.com, told The Associated Press. "One is that the current model becomes more radical, which means not making the economic adjustments it should."

Another is that "a more rational sector takes hold, one that says, 'This road will end badly, and necessary corrections must be made,'" he said.

One of the president's most trusted deputies in Congress, Carlos Kunkel, insisted on the first option Monday. If people are disenchanted, it only means that the government must intensify its transformation of the country, and not back down now, he said: "In the next two years we're going to press down a bit on the accelerator."

Argentina's economic challenges are no longer distant. The country could face a cash crunch, with international reserves falling from more than $50 billion to just $34 billion. The dollars that flow into the central bank thanks to commodities exports are no longer enough to cover imports of oil and gas.

The government is expanding Argentina's peso supply to cover the fiscal deficit and keep subsidizing electricity, natural gas and public transportation, but this feeds inflation, which analysts predict will be more than 20 percent in 2014. Meanwhile, currency controls are stifling the investment needed for significant new growth, and billions of dollars in bond payments must be made in the coming year.

Crime and inflation are the top concerns of Argentines in polls, but the government hasn't published national crime statistics since 2008, and its economic data has been suspect since 2007, when the methodology of the national statistics office was changed under Kirchner's orders.

With the specter of re-election gone, analysts say power will inevitably shift to would-be successors. And with Fernandez in seclusion, ordered by her doctors to avoid stress while recovering from skull surgery, some spoke Monday as if her mandate was already over.

"Now is the time for other people" to take charge, said Buenos Aires Mayor Mauricio Macri, who had children dress in "Macri 2015" T-shirts Sunday night after his center-right party gained ground.

Daniel Scioli, a Fernandez loyalist who governs Buenos Aires province, said the end-of-an-era talk underestimates what the government can still do. "A lot of water will flow under the bridge" between now and 2015, he said.

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Associated Press Writer Almudena Calatrava contributed to this story.