The dems run their party from the inside. As the eldest crypt keeper Schumer has control of a cadre of dem reps who will vote for whatever he tells them to. He has enough of them that he can often single handily win or sabotage (mostly what he does) whatever the democrat party is doing.

Schumer’s political platform is Israel First so he and Trump have been getting along swimmingly this term. That is why he won’t use his leverage to get impeachment votes.