Matias Delacroix/AFP/Getty Images Supporters of Venezuelan opposition leader Juan Guaido wave a Venezuelan flag as they wait for him to make an appearance in the country's capital of Caracas on Monday, March 4. In photos: Venezuela in crisis

Matias Delacroix/AFP/Getty Images Supporters of Venezuelan opposition leader Juan Guaido wave a Venezuelan flag as they wait for him to make an appearance in the country's capital of Caracas on Monday, March 4.

Venezuelan President Nicolas Maduro broke diplomatic relations with Colombia in February as tensions escalated along the two countries' borders over aid for Venezuela. Maduro denies that a humanitarian crisis exists in Venezuela and suggests that aid efforts are part of a US plot to orchestrate a coup.

With his country facing a severe economic crisis, Maduro is under increasing pressure from the United States and other countries to step down.

The opposition-controlled National Assembly has called for nationwide marches and new elections after accusing Maduro's government of "usurping power."

The United States and dozens of other countries have recognized opposition leader Juan Guaido as Venezuela's legitimate president.