A week presidential candidate, often has negative effects for those people down ticket.
Historically yes, but history didn't follow 2020 or 2022 like it should. The House was already leaning to flip back to the Dems, and if they had a big pot of money that the R's didnt and could focus it enough to push close races (PA, AZ, MT, WI, NV, etc...) toward the D column, they could look at having control in both chambers of the Legislative branch.
No money for rounding up illegals, no money for building a wall, no judges approved, any legislation that passes is riddled with pork and earmarks favoring Dems and the establishment, an impeachment every month, they could grind anything a reelected President Trump wanted to do down to nothing for two years, and then in the midterms point to him and the state of the country and say "see, he's a terrible leader, elect more of us to stop him!"