On a recent Sunday evening, about a dozen liberal housing activists from New York gathered for a virtual meeting with Senator Chuck Schumer. Though the newly anointed majority leader had served in Congress for four decades, a number of participants had scarcely interacted with him before, and some regarded him as an uncertain ally.

But Mr. Schumer was eager to offer reassurance. At one point, he described himself as a former tenant organizer who was now in a position to deliver on housing issues on a grand scale, several participants recalled.

“He had done a bunch of homework and knew everything that we were going to ask about and made a bunch of commitments with us to make it happen,” said Cea Weaver, a strategist for New York’s Housing Justice for All coalition. “He was like: I’m talking to Ilhan Omar, I’m talking to Bernie Sanders, I’m talking to A.O.C.”