They really thought by now the economy would be rebounding so their losses would not be so bad. But with only 3 more job reports before Nov 2 there is no way things will improve enough unless they fudge the figures entirely. So now they own the bad economy. Despite the mess the Dems have created or made worse they still are doing way better than they deserve to do.
Because they truly do believe that their economic ideas are the uniformly most wonderful, and they were going to bring prosperity with their high taxes and even higher spending.
As you said, they own it now, and when November comes around, they won't be able, with any sort of straight face, to blame the Republicans, though they'll try mightily to do so.