Venezuela has entered uncharted territory after the head of its National Assembly, Juan Guaidó, declared himself president of the country. He has received the backing of several governments, including the United States, Canada, and all the major economies of South America.

Nicolás Maduro insists he remains the country’s elected constitutional leader, and that the opposition, led by the United States, is attempting a coup.

The developments follow a fast-moving day of news, with hundreds of thousands of Venezuelans attending anti-government rallies in cities across the country. A pro-government rally was also held in the capital, with a far lower turnout.

“The people of Venezuela have courageously spoken out against Maduro and his regime and demanded freedom and the rule of law”, said U.S. President Donald Trump, in a statement.

Minutes earlier, Guaidó had sworn himself in as the legitimate president of the republic, on the basis that Maduro has usurped his power. The opposition claims that last year’s presidential elections, in which leading opposition candidates were barred from standing, were a “sham.” Maduro was inaugurated for a new six-year term on Jan. 10.

The Venezuelan constitution contains a provision that in the event the presidency is vacant, or the incumbent fails in his duties, the head of the National Assembly takes over in an acting capacity, pending new elections.

“Now is the moment,” Lisday Morales, 36, an accountant, said as she joined the massive anti-government crowd in the center of Caracas, the capital. “Enough is enough”.

Venezuela is mired in the world’s deepest recession, with its GDP shrinking by around half since 2014, when a slump in oil prices exposed major weaknesses in the economy. Hyperinflation is estimated – by the National Assembly, as the government does not release its own figures – to be running at around 1.7 million percent.

The opposition has been by energized by Guaidó, who became leader of the parliament earlier this month. Mr. Guaidó, 35, has led the campaign to declare President Maduro a usurper and has promised a transition to a new government. The Maduro government does not, however, recognize the authority of the assembly.

Marco Rubio, the Florida senator who advises Mr. Trump on Latin American affairs, on Tuesday issued a series of menacing tweets to Mr. Maduro. “Don’t start a fight with someone who has proven he will take actions beyond what anyone thought possible,” he wrote.

Mr. Trump has never ruled out the option of military action in Venezuela.

Michael Shifter discusses the crisis in Venezuela

CGTN’s Mike Walter spoke with the President of the Inter-American Dialogue Michael Shifter, about the crisis in Venezuela and how it is spinning out into global tensions.