Since the rise of the Tea Party movement in 2009, America’s Republicans have posed as principled defenders of the constitution. That now sits awkwardly with the announcement that President Donald Trump will declare a national emergency in order to fund the building of a wall on the Mexican border. The constitution gives spending powers to Congress, which refused him that money in the recent 35-day government shutdown. The two chambers this week agreed—rarity of rarities—on a bipartisan spending bill. It avoids another shutdown but gives Mr Trump a fraction of what he wants, for fencing not a wall. Mr Trump’s power-grab will quickly put an end to that bipartisan spirit. Though a few Republican senators chided Mr Trump’s emergency plans, expect most to fall in behind their president, while Democrats howl, plan court challenges and whisper ever louder about impeachment. There is no emergency on the border, but one is brewing in the capital.