Both of Venezuela's self-proclaimed leaders -- the country's president who retained power in a suspect election and the opposition leader who declared himself interim head of state and gained official recognition from the United States -- remained defiant Monday, with president Nicolas Maduro refusing to step aside and opposition head Juan Guaido calling for supporters to step up protests.

The 35-year-old Guaido said Sunday his supporters should take to the streets on Wednesday to pass out copies of a pamphlet proposing amnesty and some legal protections for members of the military, hoping the protections would turn the troops against Maduro.

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Guaido also asked supporters to hold mass demonstrations Saturday timed to coincide with a European Union-issued deadline for Maduro to call new elections.

“We must remain united as active agents of change in every corner of the country,” Guaido tweeted on Monday. “We’re doing well, very well, Venezuela!”

The young head of the opposition-controlled congress declared himself Venezuela's interim president last week as part of a campaign to remove Maduro. His declaration during a day of widespread anti-government demonstrations has been followed by violent clashes between protesters and security forces that have killed at least two dozen people in recent days.

Meanwhile, Maduro remained unmoved by the calls for more protests and mounting pressures from the international community, saying his government is the victim of an “economic war” led by his political adversaries with the help of Washington, Reuters reported.

Maduro maintains he is the democratically elected president of the nation and accused the U.S. of orchestrating a coup by encouraging Guaido to declare himself interim president and then leading a chorus of nations that immediately recognized his rule.

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Maduro also rejected an “ultimatum” by some European countries made Saturday that said they would recognize Guaido as president if elections were not called within eight days.

"Venezuela is not tied to Europe. This is complete insolence," he told CNN Turk on Sunday.

However, he appeared to be open to dialogue and described a meeting with President Trump as “not impossible,” according to Reuters.

The U.S. and many other nations argue that Maduro's re-election last May was invalid because his strongest opponents were barred from running -- in addition to other irregularities.

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A source familiar with the Trump administration's thinking on Venezuela told Fox News the White House is encouraged by the fact that Venezuela's Defense Attache in Washington has publicly turned against Maduro and thrown his support behind opposition leader Guaido.

The high-risk and seldom-used strategy of recognizing an alternative government that doesn't already have de facto power is tantamount to blocking Maduro's access to Venezuela's all-important oil revenue, with enormous legal and financial entanglements.

"If Maduro stays in power, Venezuela could suffer a humanitarian catastrophe," said Francisco Rodriguez, chief economist of New York-based Torino Capital.

Fox News' Gillian Turner and the Associated Press contributed to this report.