Donald J. Trump victory in the presidential race on Tuesday night capped a remarkable election in which several Democratic Senate candidates fell short and Republicans retained their majority in the House of Representatives. Here are some key takeaways from a stunning result that upended conventional expectations and set the stage for a drastic reordering of politics in Washington:

 Mr. Trump took the stage at the Hilton just before 3 a.m. and told his supporters that Hillary Clinton called him to concede the election. Striking a gracious note, he wished her well and said, “We owe her a major debt of gratitude for her debt to our country.”