This article is part of Cafe, TPM’s home for opinion and news analysis.

Significant polling errors most often result when late-deciding voters break differently from historical patterns. That’s likely to happen this year, and not in a way that favors Republicans. 

Start with the observation that the current midterm environment is utterly unlike any in recent history. The CNN average of recent polls pegs the proportion of voters who disapprove of Trump at 65 percent, and a recent You/Gov Economist poll found that of those who disapprove, 84 percent of them disapprove of him “strongly.” We’ve had no recent midterm cycle in which most American voters strongly disapprove of the president. 

If we look at the distribution of Trump disapprovers, the implications for Republicans become even more ominous. Let’s say that Trump’s most loyal MAGA voters make up 30 percent of the electorate and assume, plausibly, that most of them associate largely with........

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