Major European countries have threatened Maduro with recognising Guaido as president if free elections are not held within eight days.
In an ultimatum to Venezuelan leader Nicolas Maduro, Britain, France, Spain, and Germany have said they would recognise opposition leader Juan Guaidó as interim president unless he calls for elections.
In tweets published on Saturday, the leaders of France and Spain, Emmanuel Macron and Pedro Sanchez, said they would recognise Guado as "president in charge" if Venezuela is not given free elections.
"The Venezuelan people must be able to freely decide on their future," said Macron, as did German government spokeswoman Martina Fietz.
"If within eight days there are no fair, free and transparent elections called in Venezuela, Spain will recognise Juan Guaidó as Venezuelan president", said Sanchez.
EU also wants free, credible elections in Venezuela
In a statement, the EU's foreign police chief Federica Mogherini also urged for Venezuela to hold free, transparent and credible presidential elections "in accordance with international democratic standards and the Venezuelan constitutional order."
"In the absence of an announcement on the organisation of fresh elections with the necessary guarantees over the next days, the EU will take further actions, including on the issue of recognition of the country's leadership in line with article 233 of the Venezuelan constitution," she said.
Pressure mounts on Maduro who accuses the US of 'staging a coup'
Pressure is mounting on Maduro to hold new elections. The United States, Canada, and other South American countries have already recognised Guaidó as interim president of Venezuela.
Opposition leader Juan Guaidó has proclaimed himself Venezuela's legitimate head of state, promising a political amnesty to those who come over to his side.
At a UN Security Council meeting, US Secretary of State Mike Pompeo urged members to recognise Guaidó as interim president.
Russia, however, said at the UN meeting that it still supported the Maduro and has sent military advisors into the region.
The United Nations has called for an investigation into alleged excessive use of force by Venezuelan security forces against anti-Maduro protesters, expressing "extreme concern" that the situation could rapidly spiral out of control.
Maduro's reelection last year was contested by the opposition and criticised internationally, but he has retained the loyalty of the powerful military.
Venezuelan US defence attache leaves Maduro government to side with Guaidó
Venezuela's defence attache to the United States, Colonel Jose Luis Silva, has broken with the Maduro government, declaring free and fair elections were needed.
"Today I speak to the people of Venezuela, and especially to my brothers in the armed forces of the nation, to recognise President Juan Guaidó as the only legitimate president," Colonel Jose Luis Silva said in a video recorded at the embassy in Washington.
The move was widely welcomed by Guaidó who encouraged others to follow Silva's example.
But the news was not welcomed by everyone. In a tweet, Venezuela's Defense Ministry called Silva a "coward".