CARACAS, Venezuela — Opposition lawmakers led by Juan Guaidó will seek on Tuesday to retake the National Assembly chamber they were barred from on Sunday, setting up a showdown over President Nicolás Maduro's attempt to seize control of the last democratic institution left in this troubled South American nation.

Their bid to regain control of Venezuela’s assembly building in central Caracas would come two days after what the opposition has decried as a “parliamentary coup.” Maduro’s forces on Sunday locked out Guaidó along with other lawmakers. After a melee on the floor of the legislature, a lawmaker accused of taking bribes from the government was abruptly sworn in as head of the body.

The move appeared to be an attempt by Maduro to sideline Guaidó — the U.S.-backed opposition leader who has unsuccessfully sought to unseat Maduro for the past year — by preventing his reelection on Sunday as head of the assembly. That title has served as the basis of his claim to be the nation’s true interim leader, one that has been recognized by nearly 60 nations including the United States.

“The dictatorship will decide tomorrow if it will continue its farce, which no one recognizes,” Guaidó told reporters in Caracas. He suggested that if his entry was blocked, he would attempt to lead a session of the loyalist lawmakers elsewhere in the capital.

“We will take this risk because Venezuela deserves it,” he said. “The dictatorship is now unmasked.”

Whether Guaidó and his loyalists will be allowed to pass — and, more importantly, to conduct official business — will be paramount to assessing the extent of the damage done on Sunday to what is left of Venezuela’s democracy.

Luis Parra, the lawmaker who was abruptly sworn in as the body’s new president on Sunday — and whom the opposition accuses of being bribed to switch sides — made a public display on Monday of moving into Guaidó’s presidential office in the assembly building. In a video posted to Twitter on Monday morning, Parra was shown shaking hands with a national guardsman and sitting in the chair reserved for the body’s president. He also had a new Twitter bio up: “President of the National Assembly of Venezuela for period 2020-2021.”

Parra suggested that Guaidó would be allowed back into the chamber, as long as he is willing to participate in sessions in which Parra would preside as the body’s new president.

“Juan Guaidó will be permitted entry as any other lawmaker, and his rights will be respected,” Parra told reporters in Caracas.

Speaking with the press, Parra insisted his swearing-in was constitutional and suggested that Guaidó's attempts to convene official sessions outside the building were "not valid." He criticized Maduro and Guaidó, saying the latter did not participate in Sunday's session because he knew he would lose reelection. He hailed his new "national reconciliation" agenda, saying his lawmakers would "establish a new model of doing politics for the people, not with extremes."

“What happened yesterday is already in the past,” Parra said.

There is some chance, senior opposition figures argue, that Maduro may back off Sunday’s action in the face of broad international condemnation. Even the leftist governments in Mexico and Argentina, generally seen as more tolerant of the autocratic socialists who rule Venezuela, joined a chorus of international criticism from Washington to Brasilia to Brussels.

“The events strengthen the position of the Venezuelan democrats, and the image of the serious and coherent opposition,” said Edgar Zambrano, lawmaker and former vice president of the National Assembly. “To us and the world, there’s only one National Assembly presided by Guaidó. The rest is just a theater.”

Others candidly concede that a Maduro climbdown is unlikely. Most probable, insiders say, is that a country of which two men already claim to be president will move forward with two or even three different bodies that claim to be the nation’s true legislative branch.

Privately, some in the anti-Maduro ranks are portraying Sunday’s move as a perfect example of the kind of shrewd, if highly undemocratic, tactics that has kept the 57-year-old socialist in power despite enormous U.S. pressure and multiple plots against him.

On Sunday, the opposition managed to hold a legislative session in a newspaper building; by a 100-to-0 margin, it voted to reelect Guaidó as head of the National Assembly — albeit one much reduced in numbers and exiled from its chambers. In recent weeks, Maduro has proved able to woo — allegedly through bribes — 18 opposition lawmakers. In the days and weeks ahead, some observers fear that Maduro will gradually manage to bribe or intimidate more lawmakers into joining what is essentially a new puppet parliament.

As he does so, insiders predict, Maduro will seek to negotiate staged “breakthroughs” — including new parliamentary elections — with a “fake opposition” he more or less controls.

“This is just starting,” said one member of the anti-Maduro coalition who spoke on the condition of anonymity to speak freely. “Was it smart? Of course it’s a smart move by Maduro. Now he’s fighting a battle using the other enemies’ soldiers.”

Yet, other opposition officials insist the move will backfire on Maduro. They have grown used to the government’s aggressive tactics, which include the arrest, torture and exile of opposition members. In addition, some observers expect the United States — which has already imposed major sanctions on Venezuela — to slap additional individual sanctions on the 18 opposition lawmakers who stood with Parra on Sunday, adding a disincentive for others to defect.

 The attempt to seize control of the National Assembly building and create a puppet parliament may ultimately prompt the United States to take more provocative steps to force Maduro out.

“We are looking at additional sanctions, personal sanctions, economic sanctions that we think will bring more pressure yet on the regime,” Elliott Abrams, U.S. special representative to Venezuela, told reporters in Washington.

Leopoldo López — a political mentor to Guaidó and a prominent Venezuelan politician in his own right — predicted Maduro’s latest move would backfire.

“The dictatorship will insist on this farce that has been widely rejected by democratic countries,” said López, who has sought asylum in the Spanish Embassy in Caracas. “Even Argentina, Mexico and the ruling socialist party of Spain rejected this violent action. But constitutional legitimacy in Venezuela and democratic countries will continue to recognize Guaidó as president of the National Assembly and as interim president.”

Faiola reported from Miami. Carol Morello in Washington and Mariana Zuñiga in Caracas contributed to this report.