Larry Sabato's crew at Crystal Ball see the Dems picking up a significant number of seats in the House in 2016 at this point, and should the GOP really screw it up with a Trump or Cruz disaster at the top of the ticket, Dems winning back the House isn't totally out of the question.
Before this update, we rated 229 House seats as either Safe, Likely, or Leaning to the Republicans, 188 Safe/Likely/Leaning to the Democrats, and 18 Toss-ups. If one splits the Toss-ups 9 to 9, it would leave the House with 238 Republicans and 197 Democrats, or a net gain of nine seats for the Democrats. The new ratings are as follows: 227 Safe/Likely/Leaning Republican, 188 Safe/Likely/Leaning Democratic, and 20 Toss-ups. Split the Toss-ups, and Democrats net 10 seats, or only a third of what they need.
That is roughly what our outlook is right now — a small Democratic gain of about 5-10 seats — but as we showed earlier, the presidential math could change that calculation, swelling Democratic gains. On the flip side, Republicans still have a chance to hold Democrats to single-digits gains. A Republican net gain seems exceedingly unlikely at this point, but in this crazy cycle one cannot completely rule it out with seven months to go.
It's interesting to see that 5-10 seats is a middle point in a year where the Democrats have controlled the White House for two terms. You would normally expect the non-incumbent party to make gains, but that's how bad the GOP has it right now, even with the significant structural advantages through redistricting in 2010 and gerrymandering after that gave them a huge win in 2014.
Not only are there a significant number of toss-ups on the Republican side, but several very likely Dem pickups too. Getting enough to take back the House isn't likely, but they could gain 20 seats or so at this point.