WATCH: A brief history of VP announcement gaffes

In front of the USS Wisconsin on Saturday morning, Mitt Romney added to a gaffe to his already gaffe-filled campaign.

Welcoming his new running mate, Paul Ryan, to the podium, Romney gave Ryan his second promotion of the day.

"Join me in welcoming the next president of the United States, Paul Ryan!" Romney said.

A few minutes later, after Ryan began his remarks, Romney came back to correct the record.

"Every now and then I'm known to make a mistake," Romney said, throwing his arm around Ryan's shoulders. "I did not make a mistake with this guy. But I can tell you this: he's going to be the next vice president of the United States."

But he's in good company.

Barack Obama did the same thing four years ago, in announcing Joe Biden as his running mate:

"So let me introduce to you, the next president--the next vice president of the United States of America, Joe Biden!"

Moments later, Biden returned the favor.

"This election year, the choice is clear. One man stands ready to deliver change we desperately need, a man I'm proud to call me friend, a man who will be the next president of the United States, Barack America!"