The Senate, once again, was working into the early morning hours Friday with its new majority leader, Republican John Thune, setting the pace. It wasn’t until just after 2 a.m. that the last of the senators had straggled into the chamber to cast their vote on the confirmation of retired Air Force Lt. Gen. Dan “Razin” Caine for chairman of the Joint Chiefs of Staff. The vote capped a grinding start to the year for the Senate that included several all-night floor sessions and — importantly for Thune — the quickest top-level Cabinet confirmation process in the past 20 years.