Earlier reports suggested that the Florida senator was not in contention for a place on ticket.
FILE - In htis April 23, 2012, file photo Republican presidential candidate, former Massachusetts Gov. Mitt Romney, campaigning with Sen. Marco Rubio, R-Fla., talks to reporters in Aston, Pa. When Republican presidential candidate Mitt Romney picks his running mate, odds are he’ll select someone with far less wealth than his own. Unless he chooses Hewlett-Packard CEO Meg Whitman, one of the richest women in America. Some of the potential Republican vice presidential nominees are grappling with the same financial issues as many of their countrymen. (AP Photo/Jae C. Hong, File)
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 was not being seriously 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 in Michigan. "The story was entirely false. Marco Rubio is being thoroughly vetted as part of our process."
Earlier in the day, Romney had refused to comment on reports that Rubio, a rising star in Republican politics, wasn't under consideration as a potential running mate.
The presumptive GOP nominee initially told Fox News only that "a number of people are being vetted" but that only two people -- he and a senior adviser -- know who's on the list.
He repeated that statement Tuesday evening but clarified Rubio's status as a potential vice presidential pick.
The statement was an unusual departure from the secrecy that has surrounded Romney's process in selecting a running mate. But it speaks, in part, to Rubio's political influence among the Republican base and Hispanic voters.
The flap came on the day Rubio released a memoir and Romney concluded a six-state bus tour.
Rubio's exclusion from Romney's short list would disappoint some conservative activists, but it would not come as a complete surprise. While he offers obvious political benefits as a Hispanic leader from the swing state of Florida, Romney advisers have consistently said that Romney would give preference to those candidates with the greatest experience and ability to lead the nation on Day One. It's a reflection both of Romney's philosophy and lessons from the selection of former Alaska Gov. Sarah Palin four years ago as the GOP running mate.
A former state lawmaker, Rubio, 41, has served in the Senate for less than two years. Romney did not address Rubio's credentials Tuesday.
A handful of more likely picks joined Romney on his bus tour in recent days as part of unofficial public tryouts for the No. 2 spot. Their interactions offered clues about who Romney might choose.
Former Minnesota Gov. Tim Pawlenty traveled on Romney's bus with him for two full days, on Friday in New Hampshire and Saturday in Pennsylvania. He often warranted his own introduction, with a local official talking up his accomplishments as Minnesota governor before Pawlenty took the stage to introduce Romney.
When Pawlenty left the tour, it was to fly to New York to appear as a surrogate for Romney on ABC's "This Week."
On Sunday, Ohio Sen. Rob Portman and his wife, Jane, went along for the ride. By this time, though, Romney had been joined by a pack of family members, leaving Portman riding separately with his wife.
Less visible was Wisconsin Rep. Paul Ryan, who appeared at an event with Romney in Janesville, Wis.
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