Mr. Trump won 86 percent of self-identified Republicans — the highest percentage of that group in any Upshot/Siena survey so far this year.

He had the support of 84 percent of registered Republicans, up from 72 percent in September and also the highest of any Upshot/Siena survey this year.

Mr. Trump’s consolidation of Republican-leaning voters is a trend in national surveys, and it comes alongside a corresponding decline in the number of supporters for Gary Johnson, the Libertarian candidate, who received just 4 percent of the vote in our survey — the lowest of any Upshot/Siena poll. Republicans have been likelier than Democrats to support Mr. Johnson in most of our polls.

Even college-educated white voters, who have been skeptical of Mr. Trump nationwide, are showing less skepticism in Florida. He has a lead of 51 percent to 35 percent among those voters in our survey.