First, they are predicting how the electorate will view Trump in 11 months. Betting that more terrible facts don't emerge by then is bad bet.
Third, and related to the above, it's a near certainty Trump has been taking money from Russia and ISIS affiliate's in Turkey. He has been successful in blocking the House access to the proof but unless the @SCOTUS throws away
Fourth and finally, these vulnerable Democrats need every Democrat who voted for them last time to come out to support them. They could get a #MAGA tatoo but being a Democrat they won't get Trumper's votes. The independants are not