But it’s Donald Trump who is in command of the Republican primary, and his absence was palpable. He was the subject of the first few questions, and Jeb Bush, to his credit, used Trump as a foil throughout the proceedings. But mainly the candidates used this opportunity not to argue against Trump but to jostle for second place behind him. How that improves their overall chances of winning the nomination, I do not know.

What I find interesting is that none of the candidates on the debate stage have figured out how to respond to the issues driving Trump’s ascent. Trump focuses on four things: immigration, trade, political correctness, and a corrupt and inept system. These subjects cross partisan lines and are responsible for the unusual nature of the Trump coalition. But because Trump’s views on immigration and trade and political correctness and campaign finance are so askance from the Republican mainstream, the other candidates barely touch him.

Either Donald Trump is for real or he’s not. If his voters show up, he will be the Republican nominee for president in 2016. If they don’t, then Cruz, Rubio, even Bush have a shot at taking his place.