The 38 percent vote-share she captures is identical to the 38 percent of voters who have a favorable impression of McMahon, who was defeated in 2010 by now-Sen. Richard Blumenthal, D-Conn. More voters, 45 percent, have an unfavorable impression of her. By contrast, voters have a positive image of Shays: 41 percent view him favorably, while only 14 percent view him unfavorably, though 44 percent don't know enough about him to form an opinion. On the Democratic side, 38 percent have a favorable opinion of Murphy, while 39 percent view Bysiewicz favorably. But the percentage of voters who have an unfavorable opinion of Bysiewicz (27 percent) is higher than the percentage that views Murphy unfavorably (16 percent). The candidates are running to replace Sen. Joe Lieberman, ID-Conn., who announced this year he would not seek reelection. Lieberman's approval rating has actually soared, according to the poll, as the rest of Congress becomes less popular. Now, 51 percent of voters approve of the job Lieberman is doing, up from 41 percent in June and 38 percent in March. Voters are mixed on President Obama, with equal percentages approving and disapproving of his job performance. But despite his middling approval rating, Obama still bests former Massachusetts Gov. Mitt Romney by 13 points and Texas Gov. Rick Perry by 19 points in the Nutmeg State. The Quinnipiac poll was conducted Sept. 8-13, surveying 1,230 registered voters. The margin of error is +/- 2.8 percent. For the Democratic primary question, 447 voters were surveyed, for a margin of error of +/- 4.6 percent. For the Republican primary, there were 332 Republicans, for a margin of error of +/- 5.4 percent.