Sen. Marco Rubio (R-Fla.) has a big edge over his potential opponents in November.
Rubio leads both Democratic candidates, according to a Quinnipiac University poll released Wednesday.
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Rubio has 47 percent support, to 40 percent for Rep. Patrick Murphy (D-Fla.) if the two face off in the Senate race.
In a match-up between Rubio and Rep. Alan Grayson (D-Fla.), Rubio leads 48 to 40 percent.
The five declared GOP candidates for the seat all trail both Murphy and Grayson in head-to-head polls.
The Quinnipiac survey offered good news for Republicans in other Senate races.
In Pennsylvania, Sen. Pat Toomey (R-Pa.) has 49 percent support, with Democratic challenger Katie McGinty also at 49 percent.
And in Ohio, Sen. Rob Portman (R-Ohio) is tied with former Democratic Gov. Ted Strickland at 42 percent each.
These three seats have been a source of concern for the GOP with presumptive presidential nominee Donald Trump at the top of the ticket. Many Republicans believe Trump may imperil down-ballot Republicans with his divisive rhetoric and his lackluster fundraising efforts.
The poll surveyed 975 voters in Florida, with a margin of error of 3.1 percentage points; 971 voters in Ohio, with a margin of error of 3.1 percentage points; and 950 voters in Pennsylvania, with a margin of error of 3.3 percentage points.
— This article was updated at 10:17 a.m.