Venezuelan strongman Nicolas Maduro is bribing opposition leaders in an effort to oust Juan Guaido as interim president, a U.S. official said.

“Up to $500,000 per vote, we have been told,” Elliott Abrams, the State Department’s point man for the Venezuela crisis, told reporters on Friday.

Guaido was recognized in January by President Trump and other Western democracies as the legitimate interim president of Venezuela after Maduro remained in the presidential office following a fraudulent election. His defeat in the legislative elections would be a blow to his claim to authority under the constitution.

“Threaten, exile, detain, bribe — that is step one,” Abrams said. "Step two will be to try to grab control of the National Assembly by preventing free elections in 2020. The Venezuelan constitution calls for National Assembly elections next year, and opinion polls make it obvious the opposition will win them — if they’re free.”

Guaido is required by the country's constitution to hold free and fair presidential elections, but Maduro has clung to power for nearly a year despite U.S. pressure. The Venezuelan military has remained under his control despite some defections. Maduro’s grip on the military has been strengthened by Cuban security services, according to U.S. officials, while Russia and China have provided useful economic and political support.

“As to Russia and China, it’s interesting. If you look at — take 2019 or take the last six months or some reasonable period, there’s no new Russian or Chinese commitment to Venezuela,” Abrams said. “They’ve not diminished their political support for the regime, but I think it’s striking that they don’t seem to be willing to give him another dime, because they know it will be stolen or wasted, and I think they know the regime is going to go.”

Abrams, 71, who came to international prominence as a key figure in Ronald Reagan’s policies towards Nicaragua and El Salvador, dismissed Maduro’s claims that he hopes to “engineer a bloodbath” by noting the socialist leader’s human rights abuses.

“Thousands of Venezuelans have been killed through extrajudicial killings through this regime,” Abrams said, citing United Nations investigators. “Our focus is clear: free, fair presidential elections leading to a constitutional change of government.”

Nevertheless, Maduro has remained in power for far longer than U.S. officials anticipated when Trump gave Guaido his imprimatur in January. A senior State Department official acknowledged in April that the administration was wrong to have hoped for “an easy off-ramp for Maduro,” who allegedly has come close to relinquishing power but remained in Caracas due to Russian support.

American officials expected Venezuela’s Latin American neighbors to help put overwhelming pressure on Maduro, as a way to stop the flow of refugees into their countries. Maduro, however, has benefited from the refugee crisis because it has helped weaken the internal opposition to his rule.

“Maduro has an incredible escape valve that he’s figured out, which is to allow everyone who doesn’t like him to flee,” Fernando Cutz, a former Trump administration official, said this week. “You keep the supporters at home, you keep the ones benefiting from the corrupt regime at home, and everyone else, you know, that’s now Colombia’s problem, and Peru’s problem, and Argentina’s problem and Chile’s problem.”

Abrams maintained that Maduro will have to leave eventually. “Ultimately, there’s going to have to be some kind of negotiation among Venezuelans, and the sooner that some kind of agreement can be reached to move to free elections, the better, because that’s the way out,” he said.