Rep. Paul Ryan (R-Wis.) went out first to introduce Romney, “the next president of the United States!” Romney could hear applause, and when his intro music, Kid Rock’s “Born Free,” blared from the speakers, he and Sen. Ronald H. Johnson (R-Wis.) walked out from behind the black curtain.

“It’s completely empty!” Romney said, save for a handful of aides. “There’s nobody there. I thought, ‘Oh, boy, this is gonna look really bad on the evening news, let me tell you.’ ”

It turned out that Ryan and Johnson were in on the prank, which Romney’s traveling aides had hatched up late Saturday night. They had built a fake set for a Romney event. The applause was really a soundtrack played through a set of speakers.