“It’s the demographics that are bailing her out,” Mr. Schale said.

In Orlando, voters waited up to 90 minutes on Saturday at one early voting location at a library, some spending the time taking pictures of one another in front of candidates’ signs. Parking lots for a quarter-mile surrounding the area were packed.

Mrs. Clinton clearly carried the day there. Jon-Carlos Perez, 30, an independent voter and a concrete laborer originally from Puerto Rico, said he cast his vote for Mrs. Clinton in part because “she’s not an idiot like Trump.”

Alyssa Perez, 23, a doctoral student at the University of Central Florida who voted at another busy location in Orlando, said she considered Mr. Trump to be “anti-women, anti-Hispanic, anti-Muslim” and said, “I don’t want to live in a country where there is a president who has those kinds of views.”

Canvassing on Saturday morning in North Miami, Mary Kay Henry, the president of the Service Employees International Union, and a handful of local members focused on households, many of them Haitian or Hispanic, with an infrequent voting history. But nearly every resident who answered their door assured her they had already voted.

“The word is out,” said Ms. Henry, as roosters scooted between yards.

But it was not just Florida where Hispanics were poised to send a powerful message. In Nevada, which has the fastest-growing Latino population in the West, Democrats appeared to have built a fearsome advantage in Las Vegas’s Clark County at the end of early voting Friday, largely because of a surge of votes from Mexican-Americans. The early voting period was extended until 10 p.m. at one Hispanic grocery store in Las Vegas, where the images of hundreds of voters waiting in line ricocheted across the internet. (On Saturday, Mr. Trump claimed, without any evidence, that the hours had been extended so Democrats could be bused in.)