LAS VEGAS — “It’s like Obama in reverse! Obama in reverse!” said an excited Donald Trump supporter visiting from Tennessee who came to the Republican front-runner’s debate-eve rally in an enormous convention room off the Vegas Strip.

He meant, first, that Trump can draw huge crowds like candidate Barack Obama did in 2008. On Monday night, Trump rallied in a cavernous convention space in the Westgate hotel-casino complex; he filled about half the room, which given its size meant that thousands of people were there. Why not hold it in the Trump International Hotel 10 minutes away? Not enough room, the Trump camp said.