US Vice-President Mike Pence asked the United Nations on Wednesday to recognise Juan Guaidó as the legitimate leader of Venezuela, telling the Security Council: "Nicolás Maduro must go."
Washington will present a draft resolution to the Security Council to that end, calling on the UN to confirm the opposition leader's representative as the ambassador to the world body, Pence told the council.
"The time has come for the United Nations to recognise interim president Juan Guaidó as the legitimate president of Venezuela and seat his representative in this body," Pence said.
The United States is among some 50 countries that recognise Guaidó, the opposition leader who declared himself interim president in January, and consider Maduro to have lost legitimacy.
Maduro has maintained control with support from the military, Russia and China. Russia last month sent troops to Caracas, raising tensions between Washington and Moscow.
A draft resolution recognising Guaidó is certain to be vetoed by Russia.
A bid by the United States to win support for elections failed at the Security Council in February, with Russia and China vetoing a US-drafted resolution.
After appealing for UN recognition for Guaidó, Pence turned to Venezuela's Ambassador Samuel Moncada, who was seated in the council chamber, and said: "With all due respect Mister Ambassador, you shouldn't be here."
He advised him to return to Caracas and convey the message to Maduro that "his time is up. It's time for him to go."
The United States called the council meeting after a UN report detailed the heavy toll of the crisis from the collapse of Venezuela's oil economy.
Seven million people – 25 percent of Venezuela's population – are in need of humanitarian aid, lacking basic access to food and medical care, UN aid chief Mark Lowcock told the council.
Malnutrition rates have trebled over the past five years, particularly affecting children under five, and power outages are worsening access to clean water, threatening a major spread of disease.
More than 3.4 million people have left the country, thus triggering a migrant crisis in neighbouring countries, and that figure is expected to reach five million by the end of the year.
"There is a very real humanitarian problem in Venezuela," said Lowcock, who asked the council to support a ramping up of the international aid response.