Just a day after a Gallup poll found Democrats and Republicans even on the generic ballot question, a poll Wednesday gives the GOP a 7-point advantage.

The new poll from Democracy Corps, the Democratic group headed by James Carville and Stan Greenberg, found a generic ballot edge for Republicans among likely voters, 49 percent to 42 percent. 

The Democracy Corps poll also measured President Obama's approval at 45 percent. The poll was conducted between Aug. 30 and Sept. 2. Gallup's poll was in the field from Aug. 30 to Sept. 5.     

Gallup's numbers Tuesday had the parties tied at 46 percent on the generic ballot question. A week ago, Gallup found a 10-point edge for the GOP, which was the most significant advantage it has measured for either party in a midterm election since it began asking the question in 1942. 

It's hard to see Gallup's Tuesday numbers as a glimmer of hope for Democrats, given that Gallup is still surveying registered voters as opposed to likely voters. 

The two other major public polls released Tuesday — the NBC/Wall Street Journal poll and the ABC/Washington Post poll — both found Republican leads on the generic ballot question using a likely voter screen.

Democracy Corps measured both likely voters and what it termed "drop off voters" — those who voted in 2008 but are unlikely to vote this fall. 

Among the "drop off" voter group, Democrats hold a 47-40 lead on the generic ballot question. But among likely voters, Republicans lead 49-42.