The Republican-led Congress would have to vote to lift the embargo, something unlikely to happen ahead of the 2016 election. It might not happen quickly even if Democrats regain control of the Senate because of the strength of opposition among some powerful Republicans.
"Realizing that this issue inspires strong feelings on both sides, especially in South Florida, Clinton believes that this case is important to make at this time and place," a campaign official said.
The official requested anonymity to describe the decision-making surrounding the speech.
"Clinton will say that Republicans who remain opposed to lifting the embargo represent the politics of the past, and that changing our policy towards Cuba is a key element a forward-looking vision on U.S. foreign policy," the campaign official added.
Clinton will speak in the home state of Jeb Bush and Marco Rubio, both defenders of the embargo and both among the Republicans vying to oppose her if she is the Democratic nominee. Clinton and Bush will both address the National Urban League candidates' forum earlier Friday in nearby Fort Lauderdale.
Clinton has enthusiastically supported President Obama's outreach to Cuba over the past eight months, culminating in the reopening of embassies and full diplomatic relations this month. Obama has also called for lifting the embargo, saying it has not worked and gives the Castro regime an automatic excuse for the island country's economic woes.
Obama and Cuban President Raul Castro shook hands in April at a regional summit in Panama. It was the first meeting between a U.S. and Cuban head of state since the two countries broke ties in 1961.
As a presidential candidate in 2008, Clinton had poo-pooed Democratic rival Obama's proposal to reach out to Cuba as naive and premature. She would not commit to try to lift the embargo then. Now, she appears to agree completely that the embargo is shortsighted and unworkable.
Public sentiment may be moving the same way, but that does not mean the embargo is likely to be lifted soon. A Pew Research poll from January found 63 percent of Americans favored renewed diplomatic relations with Cuba, and that about two-thirds want the embargo lifted.
Former Rep. Joe Garcia, a Florida Cuban-American Democrat defeated in 2014, said the Clinton position embraces demographic changes and a shift in attitudes in both Cuba and the United States.
“This is about challenging the future,” Garcia said in an interview.
“Those who want to stay with the failed policies of the past are incapable of any compromise. They are running a religion, not a policy.”
Also Wednesday, Treasury Sec. Jack Lew defended the Obama administration’s efforts so far against some griping that the White House has not done enough to go around congressional opposition and make changes through executive action.
“By any measure the steps that we’ve taken are significant and dramatic changes of policy,” Lew said at a Christian Science Monitor breakfast with reporters.
“We will continue to look at other possible options, but we have, from easing travel to easing financial transactions and opening communications, opening diplomatic offices and embassies—an awful lot has changed in a short period of time.”
Karen DeYoung contributed to this report