"Even if Clinton defeats Trump by a wide margin, the House and Senate may not change hands."
http://www.bloomberg.com/politics/articles/2016-10-14/despite-the-gift-of-trump-democrats-struggle-to-win-back-congress
http://www.bloomberg.com/politics/articles/2016-10-14/despite-the-gift-of-trump-democrats-struggle-to-win-back-congress