Marco Rubio being vetted for Romney's VP slot

Mitt Romney says Florida. Sen. Marco Rubio is being "thoroughly vetted" for vice president.

The comments came Tuesday amid reports by ABC News and The Washington Post citing unnamed advisers that Rubio isn't being vetted for the No. 2 spot on the GOP ticket.

Romney told reporters Tuesday evening that he "can't imagine" who the advisers are. He says the reports are false.

I asked Marco Rubio about his chances last week.

“I'll be helpful anywhere I can be helpful, go anywhere they ask me, if it's helpful to stay away I'll do that too,” Rubio replied.

Other names are also being circulated, ranging from Louisiana's Bobby Jindal to New Mexico's Susana Martinez and Virginia's Bob McDonnell.

But few others have the popularity of Rubio. His autobiography, just released Tuesday, is skyrocketing up Amazon's charts. His Facebook page has 263,000 likes. New Jersey Governor Chris Christie has 59,000 while another possible VP pick, Ohio Senator Rob Portman, has less than half that.

Either way, they'll need someone who can fight back against a vocal Vice President Joe Biden.

"I don't know where Romney and these guys, the new Republican party are from,” Biden said. “I don't know where they were raised - they call you selfish"

His ad-libs can be problematic, but his every-man speak is seen as energizing.

"You provide the safe neighborhoods you provide the good schools you provide the school lunch programs," Biden says.

The Associated Press contributed to this report.