HOLLAND, Mich. – Republican presidential candidate Mitt Romney said Tuesday that his campaign is "thoroughly vetting" Marco Rubio as it searches for a running mate despite reports that the Florida senator is not being considered.

ABC News and The Washington Post cited unnamed advisers in reporting that Rubio, R-Fla., wasn't on the short list for the No. 2 spot on the GOP ticket.

"I can't imagine who such people are, but I can tell you this: They know nothing about the vice presidential selection or evaluation process," Romney told reporters Tuesday evening outside a Michigan ice cream shop. "The story was entirely false. Marco Rubio is being thoroughly vetted as part of our process."