But with the majority of the military still standing with Maduro, is the country stumbling towards civil war?
Maduro, for his part, stood defiant, rejecting a U.S offer of humanitarian aid that has shifted attention to Venezuela's western border with Colombia, where opponents were gearing up to try to bring emergency food and medicine into the country.
The political crisis in oil-rich Venezuela has provoked a worldwide split, with a USA -led group of countries that have already recognized Guaido as interim president pitted against nations such as Russian Federation and China that support Maduro.
Sweden, Denmark, Austria, the Netherlands, Lithuania, Finland, Estonia, Latvia, the Czech Republic, Luxembourg, Poland and Portugal also lined up behind Guaido, who last month declared himself interim president with the support of the United States and many South American nations. It is time for free and fair elections.
Speaking to reporters in Brussels after a meeting of European Union foreign affairs ministers, top EU diplomat Federica Mogherini said that "the EU and its member states never recognised as legitimate the presidential elections that were held previous year [in Venezuela]".
He said Spain, which has a large Venezuelan community, is also working on a humanitarian aid program for Venezuela, where shortages of basic items are acute.
Theresa May spoke by phone with her Spanish counterpart Sanchez on Sunday about the situation in Venezuela, the Prime Minister's official spokesman told a media briefing in Westminster.
The words of the European politicians were followed by German Chancellor Angela Merkel confirming her support for Guaido.
French Foreign Minister Jean-Yves Le Drian, speaking to France Inter Radio, appealed for an early presidential election that will ensure "the Venezuelan crisis ends peacefully".
Meanwhile Guaido, already recognized by the US, Canada, Australia and several Latin American countries, said he would soon lobby the European Union for badly-needed humanitarian and economic aid. "When asked by Sputnik to explain the decision, the ministry's spokesman Richard Walker said that it was made because the agency "hasn't been cordial" with Canadian Minister of Foreign Affairs Chrystia Freeland in the past".
Mogherini added it was not up to the European Union to recognise countries and their leaders, as it is a matter for European Union countries to decide whether they should diplomatically recognise a nation and its leaders.More news: Beyoncé and Jay-Z offer tickets for life to vegan converts
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Subsequently, Venezuela's incumbent President Nicolas Maduro blasted these actions as an attempted coup and said he was cutting diplomatic ties with the United States.
"We don't accept ultimatums from anyone", Maduro said in a defiant interview with Spanish television channel La Sexta carried out last week and broadcast on Sunday. The European Parliament has called on all EU countries to do so.
Two of the protesters, masquerading as journalists, interrupted the Lima Group's closing news conference, shouting, "Hands off Venezuela" while holding a big black sign that read "Stop the plunder".
In power since former President Hugo Chavez's death in 2013, Maduro has been accused by critics of running the OPEC nation of 30 million people like a dictatorship.
"The United States wants to return to the 20th century of military coups, subordinate puppet governments and the looting of resources", he said.
"I've turned it down because we're very far along in the process", he said in a "Face the Nation" interview.
But its statement was more measured than that of CUPE, focusing on calling for the government to "promote dialogue to foster a peaceful solution to the Venezuelan crisis".
Maduro accused Spanish Prime Minister, Pedro Sanchez, of having taken "a bad decision" in recognising Guaido.
Italy's 5-Star Movement, which makes up half of the ruling coalition, dissented from the European stance, saying it would never recognise self-appointed leaders. It aims to facilitate dialogue and is due to hold its first meeting in Uruguay on Thursday.
Prime Minister Justin Trudeau announced $53-million in new Canadian funding to support the needs of Venezuelans, including the three million refugees who have been forced to flee the humanitarian crisis in the country.