In years when the president’s party leads the generic-ballot polling average the September before the midterms, the party underperforms those polls by an average of 9.3 points. And that, in a nutshell, is why Democrats should be concerned about the 2022 elections despite their current lead on the generic ballot. This cycle so far looks a lot like former President Barack Obama’s two midterms (2010 and 2014) did for Democrats in that they lead generic-ballot polls by a few points in the September of the year before the election. But in both those years, Republicans eventually moved ahead in our generic-ballot polling average and won the election handily.
So, if Republicans outperform their early polling to a similar degree as they did in 2010 and 2014, they could win the House popular vote by 5 to 7 percentage points, which would very likely hand them control of the House (and probably the Senate too, since almost everyone votes a straight party-line ticket these days). Of course, though, that’s a big if; there has been a lot of variability in these historical trends, so a wide range of outcomes is still possible. But even if Republicans only improve their standing a little bit — something that is likely to happen, if history is any guide — it would probably still be enough to flip the House, considering that their control of the redistricting process in a plurality of states is likely to reinforce the GOP’s structural advantage in House races. Past trends don’t always hold true, but the smart money, at this point, remains on the president’s party losing control of Congress next year.