Sens. Bob Casey Jr. (D-Pa.) and Sherrod Brown (D-Ohio) are in strong position for reelection, but Sen. Bill Nelson's (D-Fla.) race against Rep. Connie Mack (R-Fla.) has tightened considerably, according to a series of new polls from Quinnipiac University.
Nelson leads Mack by 41 percent to 40, a closer margin than most polls have shown and a sign that the race might be tightening as Mack becomes better-known. President Obama also led Mitt Romney by 4 percentage points in the poll.
Casey has maintained a strong lead in nearly every public poll of his race, and this is no exception: He leads Republican Tom Smith by 49 percent to 32, while Obama leads Romney by 45 to 39 in the same poll.
All three polls were of more than 1,200 registered voters, were conducted from June 19-25 and had margins of error of 2.8 percentage points.
This post has been updated.