It hasn’t even been a week, and there’s a sense of euphoria among Republicans on Capitol Hill that no one has seen in a long time—perhaps since the first months of George W. Bush’s presidency—with MAGA-hatted tourists making their way around the chamber and a half-trillionaire doing the president’s advance work. The G.O.P., of course, controlled Congress and the White House during the first two years of Trump’s first term, but this time it’s different. After years of being bullied and stymied, Republicans are firmly behind their leader, the Democrats are in a state of near-universal bewilderment, and there’s a very real sense that the rank and file are in line and things are going to happen.