POTUS elections are much simpler to steal. Dems know they have a certain number of EVs in the bag anyway. They know some states are beyond the margin of plausibly deniable fraud. So they only need to cheat at a few choke points. The handful of purple states are where they do their cheating. And, really, just in the already deep blue cities in those purple states.
Congressional elections require district by district cheating and would require doing enough to swing dozens of districts to affect control, and dozens more to make it appear like they have a mandate. And those still need to be fairy within the margin of plausibly deniable fraud. If they make it too obvious even normal, everyday people will get riled up. As long as they can convince normies that they weren’t really cheating, or that any that did occur wasn’t enough to matter they can get away with it.
Plausibly deniable fraud?
Back in the Romney vs. Obama election, there were 59 precincts in Philadelphia that voted for Barack over Mitt by a margin of 19,305 to 0 . . . that's right,
not one single vote for Romney, even by mistake.
And Philly again had numerous "irregularities" in 2020 . . . which prompted howls of "big lie" from democrats and their lickspittle lackeys in the media.
Never mind, move along, you have no evidence of fraud, nothing to see here . . .