On his 100th day in office on Saturday, facing historically low popularity ratings, a succession of intractable foreign crises and multiple investigations of his links with Moscow, Donald Trump reminded the nation that 1 May was Loyalty Day. The day is a US tradition dating back to the cold war, when it was a bolster to stop May Day becoming a rallying point for socialists and unionised workers, but for an embattled president learning politics on the job it has an added resonance. In an interview with Fox News to mark the 100-day mark, he declared himself “disappointed” with congressional Republicans, despite his many “great relationships” with them. He blamed the constitutional checks and balances built in to US governance. “It’s a very rough system,” he said. “It’s an archaic system … It’s really a bad thing for the country.” Can we take any Republican seriously that has so little regard for a document so many a sworn to defend?