Support from the Venezuelan military is "crucial" to efforts to oust President Nicolas Maduro, opposition leader Juan Guaido wrote in The New York Times on Wednesday.
Guaido said that secret meetings had been held with members of the security forces, and that most of those in uniform agree that the status quo cannot continue.
"The military's withdrawal of support from Mr Maduro is crucial to enabling a change in government, and the majority of those in service agree that the country's recent travails are untenable," Guaido wrote.
"The transition will require support from key military contingents. We have had clandestine meetings with members of the armed forces and the security forces."
White House spokeswoman Sarah Sanders tweeted a link to Guaido's op-ed along with the message: "America stands with the people of Venezuela."
Guaido declared himself interim president last week, arguing that Maduro's reelection was illegitimate and that he, as president of the National Assembly, was constitutionally mandated to step in.
He quickly earned the support of the United States and several Latin American countries, and six major European nations have told Maduro to call fresh elections by the weekend or they too will recognize his opponent.
Venezuela -- which has the world's largest proven oil reserves -- has suffered an economic meltdown under Maduro's leadership, marked by hyperinflation and shortages of basic necessities such as food and medicine.
Millions have been left in poverty, while 2.3 million more have fled the country, unleashing a migration crisis in South America.