Rosemont, Illinois (CNN) - Marco Rubio has repeatedly pushed back against talk of becoming Mitt Romney's running mate. The Florida senator has previously said, "I'm not going to be the vice president," and in another instance suggested former Florida Gov. Jeb Bush for the job.
Despite that, Rubio's name consistently percolates near the top of many potential VP lists.
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The latest came on Friday evening, as Rubio won the vice presidential straw poll at the Conservative Political Action Conference near Chicago.
Rubio did not attend the gathering. Yet his tea party street cred and youth have made the senator a popular figure in the conservative movement. Republicans also point to his being Hispanic and from the battleground state of Florida as reasons to put Rubio on the GOP ticket.
Not all conservatives think Rubio should, or will, get the nod. Critics point to his relative lack of national experience as a reason that Romney should pass him over. Others say he's never faced the rigorous public vetting in a national campaign.
The CPAC VP straw poll likely means relatively little in the actual vice presidential selection process. However, it'll surely loom large in the guessing game.
Five other potential running mates attended the overwhelmingly conservative-friendly event: New Jersey Gov. Chris Christie, Sen. Rand Paul of Kentucky, Louisiana Gov. Bobby Jindal, former Sen. Rick Santorum of Pennsylvania and Virginia Gov. Bob McDonnell.
Each of them appeared to be in full-on VP audition mode, mounting harsh political attacks against the president.
Christie used both humor and policy swipes.
"When I landed here today in Chicago, I stopped in the airport for a minute because I heard the president was going to speak on the economy," Christie said. "I said I've got 10 minutes to waste, why not?"
The governor added: "Barack Obama's leadership is driving this business, the USA, towards a fiscal cliff. We better stand together in the next five months and stop him from doing it."
Paul called the president, "the great speech maker in chief" and accused him of "taking the last year and a half of his presidency to campaign."
In a post-speech interview with CNN, the Kentucky senator said it would be "an honor" to be considered for Romney's VP.
And the Louisiana governor followed many speakers in a sort of pep rally over Gov. Scott Walker's recall survival in Wisconsin. Jindal swiped at the president's absence in Wisconsin in the final days of the recall.
"There are many reasons maybe [Pres. Obama] didn't want to come to Wisconsin," Jindal said. "Did he not go to Wisconsin because maybe he thought he wouldn't be an asset?"
Other speakers – such as former presidential candidates Herman Cain and Michele Bachmann – also spoke.
Santorum's speech came as he emerged from a stretch of public silence to preview his political future. But on the same day that he announced the formation of a political committee and pledged to campaign for Romney, Santorum also detailed a "dual mission" of keeping Romney's feet to the fire on conservative issues.
The gathering – the first of two regional Conservative Political Action Conference events expected this year – happened in President Barack Obama's home state. The site was just a short trip from the president's downtown Chicago re-election operation.
"Conservatives take back the Midwest," blared the headline on a promotional flier that also said attendees would "take the fight for the future of America directly to President Barack Obama's backyard!"
And yet, conservatives face an uphill climb to make sweeping gains in the Midwest. According to CNN's analysis of the electoral landscape, Illinois is reliably Obama territory; and Wisconsin and Michigan both favor the president. Iowa and Ohio – two states Obama won in 2008 – are toss-ups. Only Missouri and Indiana are listed as leaning Romney.
The event was sponsored by the American Conservative Union. Thousands of conservatives attend CPAC's annual gathering in Washington D.C. Moving the event to Chicago is only the group's "second-ever regional event," organizers said in a news release.