Republicans have taken a 10-point lead on the generic ballot question in Gallup's latest tracking poll — the largest lead either party has ever held ahead of a midterm election since Gallup began asking the question in 1942.

The GOP leads 51 percent to 41 among registered voters, and Republicans are up four points from last week's tracking numbers.

Gallup notes that prior to 2010, the largest advantage for Republicans on the generic ballot question came in the summer of 2002 and 1994, when the party held a five-point edge. Republicans gained seats in both of those years, taking back control of Congress for the first time in decades in '94.

"The last Gallup weekly generic ballot average before Labor Day underscores the fast-evolving conventional wisdom that the GOP is poised to make significant gains in this fall's midterm congressional elections," writes Gallup's Frank Newport, who said the numbers suggest 2010 could be a major wave election for the GOP.


"Republicans' presumed turnout advantage, combined with their current 10-point registered-voter lead, suggests the potential for a major 'wave' election in which the Republicans gain a large number of seats from the Democrats and in the process take back control of the House," writes Newport.

One caveat Gallup does include in its analysis is that Democrats were actually ahead on the generic ballot question earlier this summer, so there is enough volatility in the electorate for things to shift ahead of November.

But as Nate Silver notes, the deficit is significant, and could be even larger than it seems. Gallup is still polling registered voters, as opposed to likely voters. The pollster will shift to likely voters closer to the fall.

Silver writes: "At FiveThirtyEight, we’ve found that the gap between registered and likely voter polls this year is about 4 points in the Republicans’ favor — so a 10-point lead in a registered voter poll is the equivalent of about 14 points on a likely-voter basis."

— Updated at 9:10 a.m.