Points to consider.
Firstly. "The only years in which the president’s party has gained net seats in Congress in midterm elections since 1906 have been in 1934 (during the New Deal), 1998 (during the Clinton impeachment), and 2002 (after the 9/11 attacks)."
Secondly. "Almost all of the Democrat Senators in competitive races who voted against Kavanaugh lost on Tuesday, while the one who voted for Kavanaugh won. The Democrats may well have hung onto their seats had they not chosen to attack Brett Kavanaugh."
Thirdly. "Trump focused his energies on the Senate, campaigning in key states in the closing weeks of the election. He found it more difficult to help House candidates, many of whom kept their distance from him in suburban areas — perhaps a strategic mistake on their part, since candidates who chose to embrace the president tended to win."
Last but not least. There is already a spat brewing regarding the failure, once again,of the electronic voting terminals not working, and in some cases under lock and key, early in the day when the Republicans traditionally vote before going to work. Another point already being "discussed" is Fox news releasing a statement claiming victory for the Dems,. when voting was still under way in some Western States. Something that has never happened before, and again being construed as a late attempt to dissuade Republican voters turning out because they thought it was all over......."It is now". :))