In this time, when it is clear that Biden will not get in without the Left, and the mentality is "anyone but trump" it is the perfect time to rally behind a revolutionary third party. A Greens/DSA/BernieBro alliance could seriously hold the election hostage. If this is not the time, when the fuck will it ever be? obviously this is not enough, but you can "hold them accountable" way more than you could hold joe fuckin biden and the democrats
because for all the good things about bernie that made him worth supporting almost the entire top of his movement was staffed by bougie careerist who immediately undercut any chance of this happening and did so with his help. the entire career path for that type of person is to lead failed leftist efforts and then get a media/party/lobbyist job. escalating things to the point where that path would get cut off would always get vetoed by that type of leadership which is why the mass revolts on the streets started and could only really start without those people leading.
it's a big part of why ultimately the top of any american leftist structure needs to be based outside of electoralism even if we participate in it.