Former New York City Mayor Rudy Giuliani confused Ohio for Indiana when introducing Indiana Gov. Mike Pence in Youngstown, Ohio, on Monday.

Giuliani's brief appearance as the GOP vice presidential nominee's opening act hit a snag when he confused the Buckeye crowd for Hoosiers, but he realized his mistake and quickly corrected himself.

"You know better than I do what a great governor he is of your state, what he's done for your state, how he's improved it and helped it and left it in tremendous condition," Giuliani said about Pence in Ohio.

After realizing his flub, the mayor swiftly explained his error.

"So, I am, I am, oh what he did for the state of Indiana. Excuse me," Giuliani said. "We're going there next."

As the mayor collected himself, he shook his head and said he loved Youngstown, Ohio, while a member of the audience shouted, "We love you Rudy."

Ohio will be a crucial swing state this fall, and its U.S. Senate race could have a determinative effect on the balance of power in Congress. Giuliani, age 72, has stumped for Trump across the United States in recent days.