Mr. Guaidó has spent most of the past week on a tour of the continent, with stops in Brazil, Paraguay, Argentina and Ecuador. These regional allies are among the 50 countries, including the United States, that have recognized him as president, not Mr. Maduro, who swore himself in in January for a second term after an election widely viewed as undemocratic.

Yet Mr. Guaidó remains a leader without a state, and any return to Venezuela could land him in prison.

“They may jail him,” said Lawrence Castro, an opposition lawmaker from Mr. Guaidó’s political party, who has himself stayed out of Venezuela until Mr. Guaidó returns. “But we have to do everything we can to enter.”

The Trump administration has threatened repercussions for the Maduro government should Mr. Guaidó be jailed. But Mr. Maduro has challenged the United States already with his detentions, which included briefly holding the Mexican-American journalist Jorge Ramos during a confrontational interview. The Maduro government has also detained Mr. Guaidó in the past and sent the police to his home.

Mr. Guaidó’s international tour appears to be an effort to ensure that doesn’t happen again.

“He’s asking, ‘If I go back and am arrested, then what will you do?’” said Alejandro Velasco, a historian of Venezuela at New York University.

The tour of regional capitals has also given the opposition time to regroup after a bruising loss over the aid shipment.