The Problem with Rob Portman

UPDATED 2:29 p.m. ET

(CBS News) -- Affable, accomplished and appropriate, Ohio native Sen. Rob Portman is high atop many pundit lists of Mitt Romney's possible vice presidential picks. He seems to be the anti-Palin; squeaky-clean and on-message. Ohio Republican chairman Bob Bennett thinks that he'd give Romney four or five crucial percentage points in the must-win state.

Not so fast, though, says President Obama's campaign in the Buckeye state. There's one descriptor they gleefully add to the list: Anonymous.

The latest Public Policy Polling data out of Ohio shows that 42 percent of voters who responded to a February 2012 poll had no opinion about him, the highest figure the polling group saw for any sitting senator.

"He's not a game changer by any stretch of the imagination," says one Obama campaign adviser in Ohio. Another pointed out that they've done their own surveys with similar findings. "We have run focus groups on him in the state where people said - Who?" Beyond the southwest pocket of the state, where Portman is from, they argue that his name is not worth much, and certainly won't excite a base.

"He's almost see through he's so vanilla," says Ohio Democratic Chairman Chris Redfern.

Portman also has a history that might not help Romney. He served as President George W. Bush's top budget expert. The Obama campaign is already arguing that Romney will take the country back to that era when the recession started. Portman's selection would reinforce that. It also plays into the Obama campaign's new slogan "Forward" - a push to remind voters that Obama's policies are of the future, whereas Romney's are economic remnants of the past. (The Romney campaign's choice of Scott Jennings, who served as Bush's special assistant and deputy director of political affairs, to run their campaign in Ohio, will only serve to strengthen those ties.)

Portman endorsed Romney on January 19 and immediately headed down to South Carolina to try to help Romney out in the primary, phonebanking alongside the candidate. He then went to work back in Ohio a month later where he opened the campaign's Columbus headquarters, helped with fundraising, and campaigned across the state with Romney.

The Romney campaign scoffs at the notion that Portman's ties to Bush, or that he's not well known enough, would hurt them in the state.

"Senator Portman is a proven fiscally conservative official and we're happy to have him on board," says Romney spokesman Ryan Williams, pointing out that the Democrats made the same Bush argument against Portman in his 2010 Senate race, where he beat Lee Fischer by a decisive 18 percent. Portman has been pushed on defending his record serving under Bush, and told the Cincinnati Enquirer in April that he stood by the work he had done in office. "I was there for just over a year and I put out one budget... actually a balanced budget. And not even over 10 years but over 5 years and I'm proud of that."

Additionally, not being a name brand may help more than it hurts. Some of the outspoken names on the short list, including Florida Sen. Marco Rubio and New Jersey Gov. Chris Christie, have baggage that team Romney may want to avoid. Romney has kept his focus on the economy, and a pick that might detract from that message is something his team will want to avoid, especially as the decision will likely be made with just about two months to go before Election Day.

Williams says that the campaign plans to use Portman as a surrogate on television and on the ground in Ohio. Today, he is holding a press conference in Cincinnati, in an effort to bracket and preview President Obama's Saturday campaign speech at Ohio State University.

Over 10,000 are expected on campus for the event, Obama's first official campaign event of this cycle. Romney has done myriads since announcing his candidacy on June 2, 2011, but has never come close to achieving crowd of that size. If Portman can successfully bracket - or even just make enough noise so that opponents take note - his value to Romney as vice presidential pick might become more apparent