he might lose some seats, but I don't see that dramatic shift, plus his supporters still support him and think he's getting poorly treated and lied about by an opposing media
popularity polling numbers are molded by the media coverage anyhow and haven't been as predictive as they once were (maybe they themselves are becoming increasingly biased, and not necessarily by design) Because there's alternative news sources AND it appears conservatives are harder to poll, polling has become much less reliable
hell, he's never been liked anyway, according to the polls, he should never have gotten to home plate never mind 1st base
what can really hurt the GOP is if they fail to deliver on any significant policy they promised, conservatives abandoned their candidates in those situations
See Poppy and "no new taxes", or Ted Stevens when a deep red state gave Obama a super majority, or the ongoing surge to Tea Party (like) candidates on the Republican side
Republicans want real changes, not lip service and political speak, so if they don't deliver they can and will lose