While experts agree a Mitt Romney-Marco Rubio ticket is unlikely, a CNN poll released Thursday showed the Florida freshman senator is the preferred pick among Republicans.

The Florida senator got 28 percent of the vote, followed by NJ Gov. Chris Christie and Rep. Paul Ryan (R-WI)–both at 16 percent–and LA Gov. Bobby Jindal at 8 percent.

Favorites including Sen. Rob Portman (R-OH) and former MN Gov. Tim Pawlenty failed to crack double-digit support, polling at six percent and four percent, respectively,

Among the Republicans polled, Rubio was viewed favorably by 50 percent and unfavorably by 10 percent.

Speculation is mounting that Romney could announce his choice during a campaign bus tour that begins Saturday and travels through four swing states, including Florida.

A Rubio source confirmed that the freshman senator is expected to join Romney on Monday when the bus tour makes stops in St. Augustine, Orlando and Miami.

The poll of 419 Republicans and GOP-leaning independents was taken on Tuesday and Wednesday. It has a margin of error of +/- 5 percentage points.

Tags | Bobby Jindal, Chris Christie, CNN, marco rubio, Mitt Romney, Paul Ryan, Rob Portman, Tim Pawlenty