WASHINGTON — A bleary-eyed Senator Joe Manchin III, the West Virginia Democrat who brokered the climate, health and tax deal that was on a glide path to passage within hours, sat silently at his desk in the Senate chamber around midnight on Saturday, gazing blankly into the middle distance as he munched on M&Ms.
A triumph was nearly at hand on a substantial piece of Democrats’ domestic agenda — but first, Mr. Manchin and his colleagues…