WASHINGTON (AP) — Chuck Schumer is used to drinking from a firehose. But the incoming Senate majority leader has never taken on such a torrent of challenges, with the opening days of both the Biden administration and Democratic control of the Senate coming at the very moment an impeachment trial gets underway. Schumer is a 38-year veteran of Congress with one overriding mandate: Help Joe Biden become a successful president. To do so, he’ll have to leverage the narrowest possible majority — a 50-50 Senate with the incoming vice president, Kamala Harris, delivering the tiebreaking vote. It’s a tough assignment.