The Trump administration has moved swiftly to try to shore up Guaido's government-in-waiting, but is struggling to move promised humanitarian aid into Venezuela with Maduro retaining control over the military.
But Maduro, who won a second term previous year in an election that critics denounced as a sham, retains the backing of Russian Federation and China and control of Venezuelan state institutions, including the security services.
It's a move created to embolden Venezuela's interim President Juan Guaido, and one that could also prove helpful for Mr Trump's re-election hopes next year.
His speech includes another demand for "Venezuelan military officials", whose power could dictate who stays in power, to choose the "clear choice - work toward democracy for their future and the future of their families, or they will lose everything they have".
"If they (Venezuelan troops) stop the aid coming through and there are pictures of hundreds of thousands of people wanting to come through from both sides, that will send out a potent message, a very powerful message to Venezuela, to everybody, that there is aid that is trying to get across, but the army is stopping it", he said.
Trump is to be joined by local officials and the secretary of state, Mike Pompeo.
Shortly after Trump ended his speech, he tweeted, "I ask every member of the Maduro regime: End this nightmare of poverty, hunger and death. The consequences will be severe and they will be swift", Rubio said, also warning Maduro not to harm U.S. personnel working in the country, adding that the United States would also respond if aid workers were targeted.
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Trump said that "socialism has so completely ravaged" Venezuela "that even the world's largest reserves of oil are not enough to keep the lights on".
"This is a moment for Venezuelans where we are determined to reach decisive moments in which we should pressure the dictatorship that has done away with rule of law, maintains political prisoners, and has persecuted many Venezuelans", Guadio said.
Mr Maduro, who denies the existence of a humanitarian crisis, dismisses the opposition moves as a "political show" and a cover for a United States invasion. Set your country free!
"We seek a peaceful transition of power but all options are open", Trump said. "Nothing could be better for the future of Venezuela!"
"Now there is a debate between the democracy and dictatorship - one between life and death", Guaido said in Spanish. But his administration has also come under criticism for not doing enough to grant asylum to those fleeing the country.
Trump used his speech at Florida International University to deliver a full-throated condemnation of socialism, saying it was "dying" across the Western Hemisphere, and branded Maduro a "puppet" of communist-ruled Cuba.