I have said this with Republicans in the minority headed into the majority and I'll say it now as they're in the majority looking at big losses in November.
The generic ballot numbers in April of an election year are noise, not signal. They tell us nothing about November. Heck, they might not even be right. The number has been bouncing around, but averaging about 6% in favor of the Democrats. If the number is still around 6% after Labor Day, I think the GOP can make real hay out of it.
But we've seen the number go up and go down. There has not been real consistency. The noise is the number. The signal is history. The party that controls the White House tends to do poorly in off year elections and every special election so far, each of which is not an indicator of anything, together paint a picture of a heavily mobilized and motivated Democrat base.
If the Democrats do not do as well in November, it is pretty easy to conclude they overreached and snatched defeat from the jaws of victory, which is something the GOP normally does.
Right now, however, there is no reason to draw big conclusions from a blip in the generic ballot, which has consistently shown the Democrats with a lead.