The late New York Times columnist Bill Safire was known for channeling the “Great Mentioner,” the unseen oracle who launched political careers into the stratosphere simply by mentioning a person’s name. Today, a more malevolent oracle is at work in Washington — call him the “Great Whisperer” — seeking to undermine the ascent of a rising GOP star: Florida Sen. Marco Rubio.

Rubio has long been at the top of nearly everyone’s vice presidential short list — and with good reason. Rubio could help deliver the key swing state of Florida, and as the first Hispanic vice presidential nominee he would give the Romney team a fighting chance with Latino voters. His humble roots and compelling personal narrative could help blunt the class warfare attacks President Obama will surely level at Romney this fall. Rubio is telegenic and a dynamic speaker who can fire up crowds and generate desperately needed enthusiasm for the GOP ticket. He is beloved by the Tea Party, and he could help Romney win over the conservative grassroots (who are still wary of an “Etch a Sketch” nominee). In short, if you were to design the perfect running mate for Romney, you would come up with Marco Rubio.

So Rubio should have the VP slot locked up, right? Not if the Great Whisperer has anything to say about it. In recent months, a whispering campaign has spread in Washington suggesting that Rubio may look good on paper, but he cannot “pass vet” for the vice presidential nomination. The whispers became more audible last October following a hit piece by Washington Post reporter Manuel Roig-Franzia, who accused Rubio of deliberately “embellishing” his family history by saying that his parents arrived in the United States after Castro took power when they, in fact, arrived during the Batista years. (I pointed out at the time that the story offered zero evidence that Rubio intentionally misled anyone).

Then in February came the revelation that when Rubio was 8 years old and living in Las Vegas, his family was baptized into the Church of Latter-day Saints and attended a Mormon church for a few years before returning to Catholicism. Rubio’s detractors pounced, ridiculously arguing that this disqualifies him from serving as Romney’s running mate, because conservatives would never accept an “all Mormon ticket.”

Rubio also faces the lingering inquiry by the Florida Commission on Ethics into a 2010 complaint that he misspent campaign contributions and abused his perch as Florida House speaker to gain a teaching position at Florida International University. Rubio calls the charges “baseless” and politically motivated and recently demanded the commission close out its investigation.

The Great Whisperer has used these stories to plant seeds of doubt about Rubio: How well do we really know this guy? What else is there in his record? Indeed, the whispers are making their way into the mainstream commentary. Even in ranking Rubio first on his vice presidential list, The Post’s Chris Cillizza writes, “We hear whispers that his time in the state legislature could be mined by a good opposition researcher.” And this month, the National Journal downgraded Rubio’s position on its vice presidential power rankings because, it claimed, Rubio “skated into office without much of his past being vetted in the media. That would change in a hurry if he’s tapped for the vice presidency, and coming four years after Sarah Palin had such trouble adjusting to harsh scrutiny, that’s a very real concern for some Republicans. After all, Tallahassee has its own secrets.” (Miami Herald political reporter Marc Caputo vigorously disputes the suggestion that Rubio was elected without proper scrutiny by the Florida press corps.)

Rubio spokesman Alex Conant explains, “The fact that that is all they can say, and they can’t point to any specifics, kind of says all you need to know.” While insisting Rubio is not interested in the VP slot, Conant says, “The idea that there is something in his background that would prevent him from seeking higher office is absurd.”

Still, Team Rubio is taking the whispering campaign seriously. After getting caught by surprise about his parent’s arrival date, Rubio wisely hired an opposition research firm to make sure there is nothing else about his past he does not know. The Florida senator has also moved up the publication date of his autobiography, “An American Son,” so that it arrives in bookstores ahead of a biography by Roig-Franzia (“The Rise of Marco Rubio”). This is potentially a high-risk move. While it allows Rubio to get the first word, if Roig-Franzia’s book contains revelations Rubio did not include it could create more fodder for the Great Whisperer.

At a time when Republicans are fielding their weakest roster of presidential contenders in a generation, Rubio stands in the wings as the GOP’s star prospect — a charismatic, talented, optimistic conservative, uniquely positioned to appeal to the fastest-growing voting bloc in the country. If selected for vice president, he could help put Romney over the top — and he would be positioned as first in line for the GOP nomination the next time around. This means that the left will use any pretext to damage or destroy him. It also means that Rubio’s success in overcoming the today’s whispering campaign could have consequences for Republicans far beyond the 2012 election.