Against a backdrop of polls that showed Mr. Biden both cutting into traditional Republican constituencies and sometimes underperforming Hillary Clinton’s 2016 showing with Latino voters in Florida, he sought to engage a broad range of voters with a stop in Tampa and, later, an expected stop in Kissimmee.

His campaign also unveiled a plan aimed at supporting Puerto Rico, which comes as Mr. Biden has faced urgent calls to shore up his standing with Puerto Rican voters in Florida, a critical constituency.

The plan goes beyond the issue of Puerto Rican statehood — Mr. Biden would defer to any decision made by the people of Puerto Rico, aides said. It also calls for accelerated access to reconstruction funding, investments in Puerto Rican infrastructure after devastating hurricanes, expanded health care and nutrition assistance, and efforts to “reduce its unsustainable debt burden,” among other proposals.