Now European countries have come on board, with Spain, Germany, France, Britain, Sweden, Denmark, Austria, the Netherlands and Lithuania calling for free and fair elections as soon as possible.
Meanwhile, in Canada, foreign ministers from Western hemisphere nations belonging to the Lima Group, which includes 13 countries that took the lead in recognizing Guaido as Venezuela's rightful leader, gathered in Ottawa to discuss additional steps to pressure Maduro.
However, not all in the European Union have offered resounding support for the National Assembly leader.
Australia, Canada and Israel are among other countries to recognize him.
Venezuelan President Nicolas Maduro delivers a speech during a gathering with supporters to mark the 20th anniversary of the rise of power of the late Hugo Chavez, the leftist firebrand who installed a socialist government, in Caracas on February 2, 2019.
"We are working for the return of full democracy in Venezuela: human rights, elections and no more political prisoners", Spanish Prime Minister Pedro Sanchez said.
"We are faced with arbitrary rule, without respect for the guarantees laid down in the Constitution or the highest principles of the dignity of the people", they said.
"The oppression of the illegitimate, kleptocratic Maduro regime must end".
At least three million people have fled Venezuela since 2015.
The 35-year-old lawmaker, who is the head of the South American country's National Assembly, declared himself Venezuela's interim head of state last month, directly challenging Maduro's claim to the presidency.
"European sovereignty is born of Member States' national sovereignty and does not replace it. Sharing sovereignty-when and where needed-makes each of our States and nations stronger", Juncker said.
Trudeau said the breakdown of democracy in Venezuela has been a years-long process that has featured "a dictatorship willing to use force, fear and coercion to retain power".
The Venezuelan government is paying both Russian and Chinese loans with oil. Critics have called that election a sham and the mainstream opposition boycotted it.
Guaido on Twitter expressed his gratitude to the European Union leaders for supporting Venezuela's fight for freedom.
In an interview with Spanish journalist Jordi Évole, Venezuela's president cited the Bible and past United States military debacles in an attempt to dissuade Washington from taking military action against Caracas.
Currently, the country is facing a severe economic and humanitarian crisis that will continue to spill over to neighbouring countries.
In 2019, the International Monetary Fund predicts that Venezuela's inflation will reach 10 million per cent, and an update to its World Economic Outlook in October estimated that consumer prices in the country would rise by 1,370,000 per cent by the end of 2018.
The opposition leader added that he would ask Europe to protect Venezuela's assets.
Trudeau announced $53 million worth of humanitarian assistance Monday for the "most-pressing needs" of Venezuelans.
Some of the EU countries backing Guaido are part of a newly formed "International Contact Group" of eight European and four Latin American nations. "It would mean opening the road to a military intervention", Alessandro Di Battista, a prominent 5-Star figure, said Sunday.
But its governing partner, the League, has backed Mr Guaido.
"I've turned it down because we're very far along in the process", he said in a "Face the Nation" interview.
The 14-nation Lima Group - made up of Canada and Latin American countries - meets in Ottawa on Monday.
"Venezuelans have the right to express themselves freely and democratically", French President Emmanuel Macron tweeted.