I don’t think the Dems can take the Senate. Even if they defeat James, the GOP is comfortably ahead in AK (Sullivan), ME (Collins), GA1 and NC. GA2 will be a runoff where the combined Republicans will win. They can’t get to 50 unless they screw Tillis and then win the Georgia runoff.
I am still worried about Collins. She has about 51% (86% of votes in) but they may crank up the fraud machine. If that puts Collins below 50% Maine has a “second choice” provision. If Biden wins, all he needs is 50 in the senate.