Sam Wang makes his predictions:

[A] Republican-controlled House and a Democratic-controlled Senate are essentially certain. Here’s why.

Based on the easily inspected database at Pollster.com, it is possible to assign a binary outcome in each of 30 swing districts based on who’s ahead. This gives a split of 18R-12D. Added to the noncompetitive races which give 212R-193D, the total is House 230R-205D.

For the Senate, the number of races is small enough that it’s necessary to be probabilistic, at least in part. Democrats will control at least 49 seats (47 Dems + Lieberman-CT + Sanders-VT). Of the five borderline races (WA, NV, CO, IL, and WV), Democrats lead in two (WA, WV), a Republican leads in one (NV), and two are within 1 percentage point (CO, IL). Splitting the last two gives Senate 52D-48D. Note that I am not making specific predictions on these five races – my meta-analytic goal is to estimate the total number of seats, not individual outcomes.