Earlier Sunday, Guaido tweeted a photo

Earlier Sunday, Guaido tweeted a photo of himself walking across an airfield ahead of his departure from the naval base in Salinas, Ecuador, where he met with Ecuadorian President Lenin Moreno on Saturday. Guaido said he was "taking off," but did not say where the plane was heading.

In Venezuela, anticipation grew ahead of the expected arrival of Guaido, who says Maduro must be replaced by a transitional government that lays the groundwork for free and fair elections in a country suffering shortages of food and medicine.

Opposition activists circulated a call on social media for people to gather Monday morning at the Alfredo Sadel plaza in Las Mercedes, a shopping and entertainment area in Caracas where protests have been held in the past. Protests were planned at other locations around the country.