Two surveys conducted this spring by SurveyMonkey for FiveThirtyEight suggest that Democrats may get the margin they need among Trump disapprovers to take back the House. In these polls, SurveyMonkey asked voters (among other questions) whether they approved of the job Trump was doing as president and whether they planned to vote for the Democratic or Republican candidate for Congress in their district in 2018. On average, the surveys found that Democratic House candidates would win 82 percent to 7 percent (a 75-point margin) among respondents who disapproved of the job that Trump was doing. (The two surveys found very similar results.) Meanwhile, House Republican candidates won by an average of 78 points among respondents who approved of the job Trump was doing. That’s slightly worse than Republicans did among those who had a favorable view of Trump in 2016, according to the exit polls.
Overall, the SurveyMonkey polls gave Democrats a 9-point lead on the congressional ballot. That’s very close to their average 10-point edge in the FiveThirtyEight congressional ballot tracker. It’s also much better than the 1-point margin Democrats lost the House by in 2016 and the 1-point lead they had in the final national congressional ballot polls before the election. And although we can’t be sure of how exactly the vote share margin will translate to a seat margin in 2018, a 9- or 10-point win for the Democrats in the national House vote would put Democrats in a good position to take back the House.