Venezuela’s opposition leader, Juan Guaidó has held secret meetings with the military to win support for ousting President Nicolás Maduro.
Earlier this month, Mr. Guaidó declared himself interim president and was immediately recognised by the US and several Latin American countries.
Major powers Russia and China back Mr. Maduro and military support is seen as crucial to his hold on power.
The crisis comes as Mr. Maduro began a second term after controversial polls. Reports say many opposition candidates were barred from running or jailed.
About three million people have fled Venezuela amid acute economic problems, and there has been an upsurge in violence in recent weeks.
US President Donald Trump tweeted on Wednesday that he had spoken to Mr. Guaidó and supported his “historic assumption of the presidency”, writing in a second tweet that “The fight for freedom has begun!”
Meanwhile, the UK Foreign Secretary Jeremy Hunt is expected to urge EU nations to impose sanctions on key figures in Mr. Maduro’s government on Thursday, after also speaking to Mr. Guaidó on Wednesday.
“We have had clandestine meetings with members of the armed forces and the security forces,” Mr. Guaidó writes in the New York Times article.
“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.”
The article also says the opposition has offered an amnesty to armed forces “found not guilty of crimes against humanity”.
As head of Venezuela’s National Assembly, Mr. Guaidó says the constitution allows him to assume power temporarily when the president is deemed illegitimate.
Venezuela’s Supreme Court has banned the opposition leader from leaving the country, his bank accounts have also been frozen.