Juan Guaido, president of the National Assembly who swore himself in as the leader of Venezuela, and his wife, Fabiana Rosales attended a pro-opposition demonstration in Caracas on Saturday. (Carlos Becerra/Bloomberg)

Key European leaders have overwhelmingly backed opposition leader Juan Guaidó as Venezuela’s interim president after President Nicolás Maduro ignored a demand by seven European Union states that he call snap elections by Sunday in a move to resolve the country’s political and economic crisis.

Spain, France, Britain and Germany followed through on their promise, and by noon Monday, 13 European nations had joined in solidarity with Guaidó, recognizing him as president. The 28-member E.U. overall, however, was unable to agree on a unified position due in part to Italy’s opposition, according to a French diplomat, who spokeon the condition of anonymity because of the sensitivity of the matter.

The United States recognized Guaidó, who heads Venezuela’s National Assembly, in late January when he declared himself the country’s legitimate leader after maintaining that a presidential election last year was rigged to keep Maduro in power. In a taped interview that aired Sunday on CBS’s “Face the Nation,” President Trump said military action in Venezuela against Maduro is “an option.”

In a statement issued Monday, Secretary of State Mike Pompeo welcomed the E.U. nations’ move and called for the “Venezuelan military and security forces to support their country’s constitution and protect all Venezuelan citizens, including Interim President Guaido and his family, as well as U.S. and other foreign citizens in Venezuela.”

Meanwhile, a USAID spokesman said the United States continues to work with Guaidó and neighboring countries to deliver humanitarian aid to Venezuela, which has been ravaged by shortages of food and medicine. Maduro has consistently refused such aid, saying his opponents have concocted the crisis.

In Europe, the most outspoken political leader against Maduro was Spanish Prime Minister Pedro Sánchez. Spain is one of the main destinations for migrants from Venezuela, many of whom have fled Maduro’s rule and the continuing humanitarian crisis. According to U.N. statistics, as many as 208,300 Venezuelans have arrived in Spain.

In a video posted on Twitter, Sánchez recognized Guaidó as interim leader and called for new elections “as soon as possible.”

“Elections that are free, democratic, with guarantees and without exclusions, in which Venezuelans decide, with their voice and vote, their future, without fear, pressure or threats,” he said. “It is, definitely, the people of Venezuela who have to decide its future.”

French President Emmanuel Macron said much the same. “Venezuelans have the right to express themselves freely and democratically,” he wrote Monday on Twitter.

After British Foreign Secretary Jeremy Hunt confirmed that his country would join those backing Guaidó, a spokesman for Prime Minister Theresa May said London was studying possible sanctions. “Venezuelan people deserve a better future. They have suffered enough, and the Maduro regime must end. It is time for free and fair elections,” the spokesman told reporters, according to Reuters. “We are looking at what further steps we can take to ensure peace and democracy in Venezuela including through sanctions.”

Speaking to reporters in Brussels after a meeting of E.U. foreign affairs ministers, top E.U. diplomat Federica Mogherini said that “the E.U. and its member states never recognized as legitimate the presidential elections that were held last year” in Venezuela. “We recognize as the legitimate institution in the country the National Assembly and recognize the role of its president,” she said.

She said the European Union will take part in a meeting with South American countries in Montevideo, Uruguay, this week “to try to find both a democratic and peaceful solution to the crisis in Venezuela.”

Mogherini added that it is not up to the European Union to recognize countries and their leaders but is instead for E.U. countries to decide whether they should diplomatically recognize a nation and its leaders. She said that later Monday a group of European countries would release a joint statement that calls for snap elections in Venezuela and recognizes the president of the National Assembly as the interim president.

In a statement, Venezuela’s Foreign Ministry rejected the announcements by European countries, accusing them of “officially joining the U.S.’s strategy to overthrow the legitimate government of President Nicolás Maduro.” The government, it said, will “completely revise bilateral relations with those countries from now on.”

Maduro fired back at his international critics during a military exercise Monday morning in the state of Aragua, east of Caracas. In the past week, the leader has attended numerous exercises and spoken to soldiers, probably because of the major role the military will play in determining his future.

“I call to reject intervention,” he said, urging the soldiers to defend the country against “Yankee imperialism.”

“The coward government of Spain has made a terrible decision in the history of relations between Spain and Venezuela. I tell Pedro Sánchez, God forbid, but if some day a coup takes place, your hands will be tainted with blood,” he said, adding that “no one imposes an ultimatum on Venezuela.” 

The European moves further isolate Maduro, who has already lost the recognition of a host of nations, including the United States, Canada, Brazil, Colombia, Argentina and Israel. 

If all European countries follow in the footsteps of the Trump administration, their decision to recognize Guaidó could potentially cut the Venezuelan government off from any accounts or assets in those countries. The Bank of England has reportedly denied a request by Maduro to repatriate $1.3 billion worth of Venezuelan gold kept in its vaults.

“The unity of positions in the modern and most influential foreign powers leaves Maduro isolated and weakened, and it strengthens Guaidó's leadership internally,” said Luis Vicente Leon, a political analyst and director of the Datanalisis polling agency.

E.U. support, opposition leaders say, may also help break the Maduro government’s narrative that Venezuela’s crisis is simply a proxy war between the United States and Russia.

“It marks this fight not as a fight of Trump versus Maduro or Latin America versus Maduro but a fight that is of the world against Maduro,” said Julio Borges, an exiled opposition politician who has been key in building Guaidó’s strategy.

In Ottawa, Canadian Prime Minister Justin Trudeau, who recognized Guaidó on Sunday as interim president, announced $53 million in humanitarian aid for Venezuela. “It’s an important moment to support Venezuelans,” Trudeau said at a meeting of the Lima Group, a 14-nation body formed in 2017 to address the Venezuelan crisis.

German Foreign Minister Heiko Maas separately announced Monday that his country would freeze $5.7 million in aid to Venezuela but would provide the funds when circumstances there allow it.

The United States promised $20 million in aid last week. In a massive anti-Maduro protest on Saturday, Guaidó said aid convoys would start to arrive this week. He said he would call for demonstrations this week to pressure security forces to let the aid in, as Maduro has refused assistance that he describes as veiled intervention by “imperialist countries.”

In Caracas, Guaidó has been welcoming each country’s move individually on Twitter. 

Early Monday, he posted Macron’s tweet and wrote: “We thank President Emmanuel Macron and the whole French government for supporting our fight. Together we will achieve the end of usurpation, the transition government and free elections for the recovery of our country. #EuropaiswithVenezuela.”

Francisco Rodríguez, economist and head of Torino Capital investment bank in New York, said that perhaps the biggest blow to the Maduro government regarding European recognition of Guaidó is that it might lose access to the European payment system.

Of Venezuela’s imports, 75 percent come from countries that recognize Guaidó. “It’ll become hard for them to make imports, as well as to make any transactions, since most of both are done through the American or the European financial system,” Rodriguez said.

Venezuela could also lose assets based in European countries, such as its 50 percent share of the oil refining company Nynas, which is valued at $374 million, according to Rodríguez’s estimates.

The economic effects remain to be seen, as countries decide whether they will assign control of accounts and assets to Guaidó, he said.

Mogherini said in Brussels last week that “further sanctions” would be considered, but any such measure would require unanimity on the part of all E.U. member states. Some, notably Italy, under the control of a right-wing populist government, have refused to recognize Guaidó.

In the words of Luigi di Maio, Italy’s deputy prime minister, Guaidó has “not been elected by the people” as president.

Krygier and Faiola reported from Miami. Quentin Ariès in Brussels contributed to this report.