Indeed, all three of these ads offer a clear reminder of why Joe Biden is such a formidable Democratic presidential candidate. If Bernie Sanders or Elizabeth Warren had emerged as the presidential nominee, Republicans would have gleefully associated numerous swing-district Democratic candidates with their left-wing agenda. Instead, even Republicans are now implicitly praising Biden in certain districts for his pragmatism as they try to drive a wedge between him and more-progressive candidates.

Republican strategists privately acknowledge that Biden is a likable candidate, boasting respectable favorability ratings even in conservative-minded districts that make up so many of the House battlegrounds in 2020. Democratic internal polling shows Biden leading in a handful of suburban seats that Trump comfortably carried in 2016—from St. Louis to Dallas to Cincinnati to Indianapolis—but where Biden is now narrowly ahead. Those are the type of districts where Republicans connected Democratic candidates to an unpopular Hillary Clinton in 2016 but aren’t able to do the same with the former vice president.

Republican officials noted that Biden is still a liability in numerous races, particularly red-state Senate contests and rural and small-town districts. One GOP operative involved in congressional campaigns said that Biden’s $4 trillion tax plan is one of the most effective issues to use against House Democrats, according to internal research. Sen. Thom Tillis of North Carolina invoked Biden’s tax plan against Democratic Cal Cunningham in an August campaign ad, one of the few explicit efforts to make Biden an issue in a Senate race.