The men who drafted the 25th amendment seem not to have thought of the possibility of a Vice President assuming the powers of Acting President while still exercising the Vice President's power to break a tie. Of course in the 1960s it probably never occurred to them that the Senate would be evenly split...they probably envisioned a comfortable Democrat majority forever. If they have to admit that Biden's condition has deteriorated to the point that the 25th amendment is warranted, how can they justify to the American people not making him resign? Harris would be able to get almost anyone confirmed as the new VPas long as they were not as toxic as AOC.
Someone like Spartacus would be able to pick up a few votes from RINOs.