But at least one key indicator suggests Trump is, indeed, doing worse than the average Republican would be doing in the same conditions — Trump doesn’t seem to be receiving the average boost an incumbent does compared to his party brethren in the House.
Look at the live interview polls (and all surveys, for that matter) taken this summer that asked about race for the presidency and the race for Congress. Counting each pollster only once in the average, former Vice President Joe Biden leads Trump by 10 points in these polls. Democratic House candidates are ahead of the Republicans by 8 points on the generic congressional ballot in these same surveys.
This goes in tandem with the fact that Republican candidates for the House are less likely than Democratic candidates to release internal polls that include a presidential result. In theory, this would indicate that Trump is weak in their districts.
The fact that Biden’s lead is wider than the House Democrats’ edge is unusual. If it holds, it would be historic.