Trump called Guaidó the “true and legitimate” leader of Venezuela and said President Nicolas Maduro is a “tyrant" as lawmakers applauded.
“Mr. President, please take this message back to your homeland,” Trump said to Guaidó. “All Americans are united with the Venezuelan people in their righteous struggle for freedom.”
Guaidó's attendance as a surprise, last-minuted guest of the president came as he has been trying to win face time with Trump, his most important international ally. Guaidó's visit to Miami on Saturday rounded out a two-week world tour that took him first to Colombia, then across Europe and Canada, where he held meetings seeking more international help to oust Maduro.
Venezuela has been a top priority in Latin America for the Trump administration, which a year ago was the first among a coalition of governments to recognize Guaido as president.
The U.S. and nearly 60 other governments say Maduro's 2018 re-election was not legitimate and that Guaido, as leader of the National Assembly, should be named interim president under the Venezuelan constitution.
Maduro, however, remains in control, having faced down a failed military uprising, a brief renewal of mass anti-government protests and U.S. sanctions.
Earlier, the White House said Ivan Simonovis, the former police chief in Caracas who was imprisoned in 2004 and held in captivity for nearly 15 years, also would be a guest. Simonovis was sentenced to 30 years in prison on what he considered trumped-up charges of ordering police to fire on pro-government demonstrators during a coup against then-President Hugo Chavez.