A new poll from Quinnipiac shows incumbent Democratic senator Bill Nelson of Florida maintaining a slight lead over his likely Republican challenger, Congressman Connie Mack. The poll shows Nelson with 43 percent support from registered voters in Florida, with Mack receiving 39 percent. This margin has remained mostly constant, although Mack actually had a one-point lead over Nelson in Quinnipiac’s May poll of the race.

Nelson’s edge over Mack may be attributed to his 11-point lead among independent voters, as well as the fact the poll is of registered voters instead of likely voters, a measurement that has been shown to be biased toward Democrats.