Then Romney says, "... the next president of the United States, Paul Ryan."
Snickers and puzzled expressions muted a building ovation for a heartbeat or two. But then came a throaty outburst, nearly drowned out by heroic movie-theme music loud enough to be felt through the pavement, as Ryan bounded down the bunting-draped steps from the Wisconsin, gave Romney a quick hug and joined him in waving to a crowd aflutter with flags.
After Ryan had already launched into his speech about unabashed budgetary austerity, traditional values and the failures of President Barack Obama's Democratic White House, Romney stepped back onstage to smilingly correct his gaffe.
And it was quickly forgotten.
After all, Obama made the same flub four years ago introducing his running mate and corrected himself instantly: "So let me introduce to you, the next president the next vice president of the United States of America, Joe Biden!"
Four years later, this conservative-heavy crowd wasn't distracted from rejoicing that Romney had chosen one of them, not some mealy-mouthed moderate.
Cheers of "USA, USA," broke out as Ryan spoke about how America was founded on an idea and the sun broke through the clouds midway through the speech.
"I'm telling you, I loved it, every bit of it," said Harry Faircloth of Chesapeake, a burly retired Army officer who was a paratrooper in Vietnam. Faircloth said he'd followed Ryan's congressional career and his efforts to "get a handle on the finances of this country."
"I got kids and grandkids and we have to change the way things are being done so they'll have a country," he said.
Margaret Lewis, wearing an American flag sweater, said the newly minted pairing of a Mormon and a Roman Catholic running mate gave her hope that they would champion moral values, such as restrictions on abortion and gay rights. "I think we need religion back in this country, we need the Lord's Prayer back in schools," she said.
His debut address over, Ryan's family joined him, and he embraced his daughter and two sons before kissing his wife, Janna, and stepping off the stage and into the race for the White House.
For the crowd, at least, the emotional, carefully orchestrated event overwhelmed the hitch at the beginning.
"My reaction was to laugh it off," Arleen Crawford, 57, a speech therapy teacher for public schools in nearby Virginia Beach, said about Romney's momentary lapse. "Then my next reaction was, 'Oh Lord, there it is, the faux pas they're looking for."
Kasie Hunt contributed to this report.