MEXICO CITY (Reuters) - Mexican leftist Andres Manuel Lopez Obrador was rushed to hospital for surgery on Tuesday after suffering a heart attack, which could undermine his ability to lead protests against President Enrique Pena Nieto's push to open up the oil sector.
Lopez Obrador, who was runner-up to Pena Nieto in last year's presidential election, is perceived as one of the biggest threats to the planned reform to open the state-controlled oil sector to private investment.
Patricio Ortiz, the cardiologist who attended Lopez Obrador, told a news conference that he was making "satisfactory progress" and was conscious. He could not say how long Lopez Obrador would remain in hospital.
Lopez Obrador underwent an angioplasty procedure, a technique that involves inserting a plastic tube to widen narrow or obstructed arteries.
Mexico's peso currency rallied after news of Lopez Obrador's hospitalization, economists said, pointing to the possibility that his health problems could weaken protests against the energy reform.
Giving a televised address on education, Pena Nieto expressed his concern and wished Lopez Obrador a quick recovery.
A fiery orator and icon of the Mexican left, Lopez Obrador's closest brush with the presidency came in 2006, when he was narrowly defeated by conservative Felipe Calderon, and spent much of the next six years saying he had been robbed of victory.
Lopez Obrador made the same accusation against Pena Nieto last year and has sought to build a popular front against the energy reform plan, claiming the president wants to sell off Mexico's assets by luring foreign capital to the oil industry.
The reform is the central plank of Pena Nieto's economic reform drive, and is due to be debated in Congress in the next few days and is expected to pass before Christmas.
Lopez Obrador has sworn he will work to undermine any contracts between the government and private oil companies.
Since losing to Calderon in 2006, when his protests against the outcome brought much of the capital to a standstill for weeks, the silver-haired Lopez Obrador has kept up a hectic schedule, touring Mexico in a near-permanent campaign.
Days ago, Lopez Obrador vowed to form a human circle around Congress to protest against the energy reform.
Lopez Obrador's son, Andres Manuel Lopez Beltran, told a news conference that the protest called by his father would go ahead in his absence and invited demonstrators to assemble at the Senate on Wednesday morning.
However, recent protests have failed to muster the scale of support he achieved in 2006 when hundreds of thousands took to the streets of Mexico City.
(Reporting by Mexico Newsroom; Editing by Jackie Frank, Philip Barbara and Eric Walsh)