Republicans lead by 51% to 41% among registered voters in Gallup weekly tracking of 2010 congressional voting preferences. The 10-percentage-point lead is the GOP's largest so far this year and is its largest in Gallup's history of tracking the midterm generic ballot for Congress.
And that's among registered voters. When you narrow the sample down to likely voters, the lead almost certainly grows even larger.
The ten-point lead is twice the size of the previous-largest ever margins, five point leads in June 2002 and July 1994.
Republicans gained eight House and two Senate seats in 2002, defying the trend of the president's party losing seats in the midterm elections. They captured 54 House and eight Senate seats in 1994, winning control of both chambers for the first time since 1954.