But, according to media reports, security forces loyal to Maduro blocked Guaido and many of his allies from entering the building. One video showed Guaido trying to scale the gate and being pulled down by security forces, some of whom carried shields to push back the crowd.

#AHORA Momento en el que Juan Guaidó trató de entrar a la Asamblea Nacional saltando una cerca, mientras juramentaban a Luis Parra como nuevo presidente del parlamento. pic.twitter.com/BfC7UQaYa1 — Gregory Jaimes (@GregJaimes) January 5, 2020

The vote that followed gave the Assembly leader’s post to Luis Parra, a rival of Guaido’s, according to media reports. In the extraordinary confusion, some observers insisted there was no quorum for a vote. Parra, described in some accounts as a “dissident opposition politician,” has been accused in a recent corruption scandal, and U.S. officials suspect he is allying himself with Maduro in trying to take over the Assembly.

U.S. officials denounced the events and said they would not recognize Parra’s claim.

Guaido “remains #Venezuela’s interim president under its constitution,” tweeted Michael Kozak, the State Department’s acting assistant secretary for Western Hemisphere Affairs. “This morning’s phony National Assembly session lacked a legal quorum. There was no vote.”

Later Sunday, Guaido gathered lawmakers in a separate location to cast what the opposition said was the real vote, which he won easily. Secretary of State Mike Pompeo sent out a statement on Sunday night congratulating him on his re-election.

Guaido’s claim to be “interim president” of Venezuela is recognized by the U.S. and more than 50 other countries, many of them in Latin America. The coalition has been alarmed by Venezuela’s descent into autocracy and economic despair under Maduro.

U.S. officials say they retain confidence in Guaido, notwithstanding fractures and scandals in the Venezuelan opposition and despite widespread frustration that a year’s worth of pressure, including a failed high-profile uprising attempt , has not led to a change in government in Caracas.

In an interview ahead of Sunday’s vote, Elliott Abrams, the Trump administration’s special representative for Venezuela, stressed that Guaido is the Venezuelan opposition’s choice for interim president and that the U.S. backs him as a result.

“We continue to support him fully,” Abrams said. “There is no reduction in support at all in the United States.”

He also confirmed that the Trump administration intends to ramp up the economic pressure on Maduro and his allies in the months ahead. That will primarily involve imposing more economic sanctions on individuals, companies and other entities linked to the Maduro government.

Companies in other countries that do business with the Maduro government may face new U.S. sanctions, too. Venezuela is a top oil producer, making it a tempting partner for nations seeking energy resources. The U.S. has sanctioned PDVSA, a major Venezuelan state-owned oil firm.

Abrams dismissed claims that the United States is running out of targets to sanction, saying that the Trump administration keeps getting “more and more information from cooperative governments and individuals” about new targets tied to the Maduro government.

The U.S. also hopes to see the European Union and other Latin American countries step up their own imposition of sanctions on Maduro. Abrams downplayed frustrations with the lagging international sanctions effort, noting that unlike the U.S., many other countries have not traditionally used sanctions and thus lack the necessary expertise and architecture.

“It’s slow because it’s new,” he said.