“The Hispanic vote in Florida was reliably conservative and now is becoming reliably Democrat,” said Fernand R. Amandi, a pollster who has extensively surveyed Latinos in this crucial swing state whose 29 electoral votes are very much up for grabs, and could determine the outcome of the presidential race.

Still, much remains up in the air. Strong Latino candidates who are Republicans, like Senator Marco Rubio, still command loyal votes. And in Miami, Representative Carlos Curbelo, a Cuban-American Republican, and Joe Garcia, a Cuban-American Democrat, are in close duel in which Mr. Garcia is trying to retake the congressional seat Mr. Curbelo won from him two years ago.

There are few places in America where Latino voting power is as fluid as in Florida. Here are three snapshots.

Lured by Change

MIAMI — Ms. Flores was never enamored of politics. But the more she heard her bosses, a group of lawyers, talk, the more she realized she had a kinship with Democrats on issues that affected her. As with so many people who switch parties, her decision was also driven by the top of the ticket, Barack Obama, in 2008.

“I was a single mom with two kids, and he represented change, and helping people like me, and equality,” she said.

She worried about getting laid off. She worried about how she could afford to get her son a car and pay for college. Yet, she said, the Republican Party didn’t speak to her. Instead, it fumed about abortion and religious rights and immigration. “It was ‘God says this and God says that,’” she said.