Warp,
How certain are you that the Dems being ineffective would be a bigger reason for a Trump win than an all-in base wanting him back? And note that the ineffectiveness of the Dems derives in good measure because The Turtle has made blind opposition his mantra. That the first part of the infrastructure package got some Repub support is almost a miracle, but to totally oppose a bill that is many years (decades, really) late and which most conservatives want would be a bad look indeed.
The GOP modus operandi of obstruction, then saying how the opposition is doing nothing, is cynicism of the highest order. And when the Ds get some occasional 'win' in spite of R opposition, the Rs will still take credit and crow to their electorate of the goldfish-like memory, thus benefitting at both ends.