Republicans led Democrats by 10 percentage points in Gallup’s most recent weekly poll of Congressional voting preferences, the largest lead for the GOP in Gallup’s history of tracking the midterm generic ballot.

Gallup’s survey of 1,540 registered voters found 51 percent preferred Republicans in the 2010 Congressional elections, while 41 percent preferred Democrats. The survey was taken Aug. 23 to Sunday and polled a random sample of voters in all 50 states and the District of Columbia. This is the fifth consecutive week that the GOP has held the advantage.

Gallup began tracking the generic midterm ballot in 1942. The GOP’s largest previous lead was 5 percentage points in June 2002, while Democrats have regularly enjoyed far larger leads. The widest was 32 points in July 1974, just before President Richard Nixon resigned.