(CNN) President Donald Trump's struggles in the polls have been well documented. He entered the final debate down about 10 points to former Vice President Joe Biden and trailed in key swing states.
Less discussed is that Trump has hurt Republicans' chances of holding onto Senate control and pretty much eliminated any shot that they take back the House.
Let's start in the Senate. Republicans still have a non-nominal chance of keeping a majority, but Democrats are favored. Democrats need a net gain of three seats to win control if Biden wins the presidency because his vice president, Kamala Harris, would break any tie.
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Assuming Republicans knock off Alabama Sen. Doug Jones (he's trailing by double digits), Democrats will need to win four Republican-held seats to reach that net gain of three. They're ahead in at least five races: Arizona (by 7 points), Colorado (by 9 points), Maine (by 5 points), Iowa (by 2 points) and North Carolina (by 3 points).
What's important to note is that in all of those states, Biden is ahead of Trump. This includes three states (Arizona, Iowa and North Carolina) where Trump won in 2016. In fact, the difference between Biden's polling margin and the Democratic Senate candidate's margin averages just 3 points.
The fact that these Republican senators are being weighed down by Trump shouldn't be a surprise. The correlation between Senate and presidential results has climbed much higher in recent years. The 2016 election was the first time since senators were popularly elected that every state voted for the same candidate for Senate and president.
This year, the same thing may happen. The only state where there is a mismatch at this point is in Georgia, where Republican Sen. David Perdue and Biden both hold a within the margin of error lead.
(The limited polling in Georgia's special Senate election does indicate that Democrat Raphael Warnock leads both of his likely potential Republican challengers in a very probable runoff, though that election is likely to be decided in January when the presidential race is not on the ballot.)
One piece of good news for these Senate Republicans is that anything that helps Trump is likely to help them. If Trump improves his standing in the presidential race, they'll probably benefit.
The chance of Republicans recovering in the race for the House is much lower. They lost their majority in 2018, when Republicans lost almost every single seat in districts carried by Hillary Clinton in 2016.
This year, Republicans' chances at a House majority have been all but squashed because they're doing poorly in what should be red territory.
Take a gander at the about 20 seats where Trump and the House Republican carried in 2016, but where the Democratic candidate won in 2018. The Republicans aren't clear favorites in any of these seats. Trump won in these districts by an average 6 points, but in an average of the forecasts from FiveThirtyEight and Jack Kersting, the House Democratic candidate is favored by 7 points in 2020.
The main problem for Republicans is Trump just doesn't seem as popular as he once was. Look at Maine's 2nd district, New Jersey's 2nd district and New York's 22nd district. Trump won them by margins ranging from 5 points (New Jersey's 2nd) to 16 points (New York's 22nd). Today, polls have Trump doing 9 points to 17 points worse than he did in 2016. He is ahead in none of these districts. Not surprisingly, the Republican House candidate faces a deficit in all these districts.
Perhaps most interesting is New Jersey's 2nd district. Rep. Jeff Van Drew was elected as a Democrat but became a Republican once in office. That may have seemed like a smart move at the time, given Trump won the district in 2016. Right now, however, it looks like it might not work out for him.
If Van Drew does win, it may be a sign that Republicans are going to do better in the 2020 elections than we currently think.