Poll: Chances Dems win control of the House in 2018?

[Virginiá]

Right now the most I feel comfortable with is 25%, but only because it's so soon and I'd really like to see a bunch of generic polls for 2017 first.

But given everything we know about Trump, his perpetually awful favorables/approvals, the GOP's (and his) plans and the growing backlash to it, I think the conditions are certainly there for a wave against the GOP. Not that it is guaranteed, but I have trouble seeing how 2018 is even a neutral year at this point.

That being said, taking back the House is quite a feat. I think it's slightly more likely that Democrats narrow it to a razor thin GOP majority, though I think a takeover is completely plausible. If I start seeing generic poll numbers for Democrats that resemble late 2005/early 2006, I'd feel comfortable saying they have a good chance at it. Other than that, I think the real action in a backlash midterm will be in the states, where Republicans are overextended and vulnerable, at least in terms of Governors. A good year for Democrats in the states will help pave the way for more frequent House majorities in the 2020s.

[Virginiá]

The Democrats tend to not do well in midterm elections in the House, period. Their 3rd best midterm since 1974 was only a gain of 7. 1982's +26 and 2006's +30 really pale in comparison to 1994's +54 and 2010's +63.

They do pale in comparison, but in 2010 Democrats were significantly overextended. Same for 1994, although that was the dawn of a new playing field. The GOP getting those large blowouts doesn't mean all that much. They have an advantage in the House that has increased somewhat over the past 6 years, that's it.