Florida Sen. Rubio keeps mum on Romney's VP search

By the Associated Press | June 20, 2012 | 8:20 AM EDT

FILE - In this May 24, 2012, file photo, Sen. Marco Rubio, R-Fla., speaks just off the Senate floor on Capitol Hill in Washington, during a series of votes. Republican presidential candidate Mitt Romney is staying mum on whether Rubio, a rising star in Republican politics, has been eliminated from his short list of potential running mates. The presumptive GOP presidential nominee told Fox News on Tuesday, June 19, 2012, that "a number of people are being vetted," but that only two people, himself and a senior adviser, know who's on the list. (AP Photo/J. Scott Applewhite, File)

WASHINGTON (AP) — Florida Sen. Marco Rubio isn't shedding much light on Mitt Romney's search for a running mate even after the Republican presidential candidate said his campaign was checking out Rubio.

The 41-year-old first-term senator, a rising GOP star, is firm in saying he won't discuss Romney's selection process.

Rubio says he's confident Romney will make an "excellent choice" and that those who support Romney "should give him space to do that."

Romney said Tuesday that his campaign is "thoroughly vetting" Rubio, and he took issue with reports about who was and wasn't on the short list for the No. 2 spot.

Rubio was asked Wednesday on "CBS Early Morning" about what happens in the background checking process. He quickly shifted topics to the recent release of his autobiography, "An American Son."