Early Look At 2018 Generic Ballot: Democrats have a 7.2-point advantage in FiveThirtyEight.com’s 2018 generic ballot tracker, standing at 44.1% to Republicans’ 36.9%. According to FiveThirtyEight.com’s analysis of generic ballot results since 1942, the standing of the president’s party 18 months before a midterm election is generally close to their final vote margin. If this trend holds, as it often does for the party out of power, Democrats’ lead today may translate into a roughly eight-point lead in the national House vote next November. According to generic ballot data from the eighteen midterms since 1946, the final numbers were only off the final margins by an average of two percentage points.
The Democrats’ lead today does not automatically mean they will win the national House vote by a large enough margin to gain control of the House next year, however. There are just 23 Republican-held House seats in districts won by Clinton, offset somewhat by twelve Democrat-held House seats in districts won by Trump. By comparison, in 2010 Democrats had to defend 48 seats in districts McCain won. Republicans can successfully defend their majority by delivering on election promises and minimizing retirements. Running strong candidates and campaigns in these competitive districts will be key.