Venezuelan opposition leader Juan Guaidó has said he is considering asking the US to launch a military intervention in the embattled country.
Speaking to the BBC's Nick Bryant, he said he would "evaluate all options" to oust President Nicolás Maduro.
Last week he launched a failed attempt to spark a military rebellion and force Mr Maduro out of power.
The president responded by delivering an address from an army base in Caracas, flanked by soldiers.
Mr Guaidó declared himself Venezuela's interim leader in January. As the head of the opposition-controlled National Assembly, he invoked the constitution to assume an interim presidency, arguing that Mr Maduro's re-election last year was illegitimate.
But Mr Maduro - who is backed by Russia, China and the leaders of Venezuela's military - has refused to cede power.
Mr Guaidó has the support of more than 50 countries, including the US, UK and most Latin American nations - and he has told the BBC that US support for him has been "decisive".
"I think President [Donald] Trump's position is very firm, which we appreciate, as does the entire world," he said.
Asked whether he would like Mr Trump and the US military to intervene, he responded it is "responsible to evaluate" the possibility of international intervention, adding: "I, as the president in charge of the national parliament, will evaluate all options if necessary."
What has the US said?
Mr Trump told reporters on Friday that he wasn't looking to get the US military involved in Venezuela.
He said that in a call, Russian president Vladimir Putin had assured him that "he is not looking to get involved in Venezuela other than he'd like to see something positive happen for Venezuela", before adding: "And I feel the same way."
But Secretary of State Mike Pompeo had much stronger words for Russia on Sunday, telling the US broadcaster ABC that "the Russians must get out".
"It's very clear, we want the Russians out, we want the Iranians out, we want the Cubans out," he said.
Has Guaidó been defeated?
In response to the clashes this week, Mr Maduro appeared on Friday flanked by soldiers at an army base in Caracas, calling on the armed forces to defeat "any coup plotter".
"No one dare touch our sacred ground or bring war to Venezuela," he added, in a show of defiance that followed days of clashes. Four people died in the violence, including two teenagers.
But Mr Guaidó denies that he has been defeated, telling the BBC that President Maduro "has been losing again and again".
"I think the only one who really hurts himself is Maduro," he said. "He has been losing again and again. He is increasingly weak, increasingly alone, and has no international support. On the contrary, we gain acceptance, support and future options."
He also claims that it is "clearly visible that the armed forces no longer support Maduro".
How did the violence unfold?
On Wednesday, both pro- and anti-government supporters held demonstrations in Caracas which were initially peaceful.
There were reports of gunfire in the city, and a local NGO, the Venezuelan Observatory of Social Conflict, said Jurubith Rausseo, 27, had been shot dead during a rally in the opposition stronghold of Altamira.
At least 46 people were injured in clashes between opposition supporters and the security forces.
On Tuesday, Mr Guaidó declared what he called the "final phase" of the operation to topple Mr Maduro. He posted a video of him with a number of men in uniform and said he had the support of "brave soldiers" in Caracas.
He urged Venezuelans to join them on the streets, and appeared alongside another opposition leader, Leopoldo López, who had been under house arrest after being found guilty of inciting violence during protests in 2014.
Spain's government later said that Mr López and his family had sought safety in their embassy, but said the opposition figure had not claimed political asylum.
An arrest warrant for violating the house arrest order was issued for Mr López, according to a statement on the Supreme Court's website. The order stated that Mr López should continue to serve the rest of his 13-year sentence in prison.
Spain said it had no intention of handing over Mr López to the Venezuelan authorities.