I dont think that polls should be paid attention to until late Sept-early Oct. Trends tend to go back and forth until then.
But, having said that, an incumbent behind at this point? Point to Reagan and we can all see what is about to happen.
Yet, the most important elections are still in the Congress.
Get enough conservatives in there and the present leadership can be ousted. I can see DeMint as Senate leader. And a outside conservative as Speaker of the House.
The vast majority of House members will be reelected. Unless there are many Tea Party candidates running and winning against Dem incumbents,and I doubt there are, the House leadership will remain unchanged. Though several Tea Party freshmen are likely to go down, Kristie Noem for one. As for the Senate, it would take the removal of half the GOP senators to accomplish your goal.The likleihood is that there will be just enough pick up to get a majority (3 or 4 seats). Nowhere near enough to dethrone the GOP leadership. The candidates have already been chosen and the numbers for what you suggest are not there for either house. These battles are won or lost in the primaries not the general.