Let's face it: Mitt Romney's presidential campaign could use some pizzazz, and where better to find it than by choosing Florida Sen. Marco Rubio as a running mate?

Sen. Marco Rubio (R-Fla.), signs a Romney sign for a supporter at a rally for presidential candidate Mitt Romney at C.C. Ronnow Elementary School in Las Vegas, July 28, 2012. (John Locher/Associated Press)

I first heard Rubio speaking to CPAC, the American Conservative Union's annual conference, in 2010. Listening to the speech on POTUS, the SiriusXM political channel, I've gotta say I was impressed.

First, Rubio has charisma — even over the radio. He's a great public speaker. Four years ago, a lot of folks were initially jazzed by Sarah Palin's magnetism when John McCain selected the former Alaska governor as his running mate, and many still are. But Rubio has something more.

His CPAC talk featured substance, specifics on lowering corporate tax rates, abolishing capital gains and estate taxes. He talked tough on terrorism. For a listener, Rubio came off as far deeper than Palin ever has.

Also, Rubio has a great backstory — even if he may have fudged it a bit in the past. The son of Cuban-born parents, a bartender father and a mom who worked in a factory, at Kmart and as a maid, Rubio's success story offers a sharp contrast to the Romney family story of inherited wealth and privilege.

Finally, Rubio could be a big help to Romney in the swing state of Florida. A recent Public Policy Polling survey indicated that Rubio could help the GOP ticket in his home state. 

The GOP might hope that Rubio could help gain Hispanics nationwide, too. He's certainly exhibited a more open attitude than many Republicans on helping young immigrants who've lived in the United States most of their lives even if they're here illegally.

But the Latino community isn't monolithic. Puerto Ricans, a significant voting group in Florida, might be offended by Rubio's opposition to the appointment of Sonia Sotomayor to the U.S. Supreme Court. More recent Mexican immigrants might not relate to Rubio's tales of struggles in the Cuban community, now a well-established power bloc in Florida.

Romney's campaign persona is much improved since I first saw him at a Denison, Iowa, coffee shop in 2007, looking buttoned down in a blue suit and sounding scripted amid unnecessary TV lights. His brief talk to Coloradans from a picnic table last week showed a more relaxed candidate, but he still comes off as a bit, well, dull sometimes.

Rubio would be a perfect antidote to that — a vice presidential candidate who could enthuse the base, but with a gravitas the last GOP veep nominee lacked.

Sandra Fish teaches journalism at the University of Colorado and has reported on politics in Iowa, Florida and Colorado. Follow her on Twitter at @fishnette