As Republican presidential hopeful Marco Rubio fielded questions near the end of a campaign stop here Wednesday morning, one man wondered aloud about the comparisons that have been drawn between the Florida senator and President Obama.

“You are an extremely articulate, energetic, bright, young first-term senator. That reminds me of somebody eight years ago,” the man said. The crowd chuckled knowingly.

The parallel highlighted how Rubio’s youthfulness and his résumé could hurt him in the GOP primary. His ardent rebuttal reflected his sharp desire to make sure that doesn’t happen.

Rubio gave an animated response, arguing that Obama was a “backbencher” in the state legislature while Rubio was the Florida House speaker and that he has served longer in the U.S. Senate than Obama did when he launched his White House bid.