Former Mississippi Gov. Haley Barbour is entrenched in fundraising for American Crossroads, so FEC rules dictate that he can't dole out advice to Republican presidential nominee Mitt Romney directly. But the Republican heavyweight did have a pointer or two (it is Gov. Barbour after all) on how Mitt Romney should be prioritizing his veepstakes. [See Photos of Joe Biden on the campaign trail.]
"I don't think people doubt this will be a very hard, very tough, very negative and probably very close race," Barbour says. "I can't imagine anybody being Polyannaish enough to think this is going to be easy."
"In the vice presidential picking business, the first thing you got to do is decide what do you want to accomplish," Barbour says.
Former President John F. Kennedy chose Lyndon Baines Johnson to help him win the South, Ronald Reagan picked George H.W. Bush to unite the Republican party and Barbour says Romney has to decide if he has his eye on a particular state, constituency or goal before he settles on the best person for the job.
Barbour said during a breakfast meeting with reporters Friday that rule number one is the Hippocratic oath of presidential politics that says: "Do no harm." [See: Latest political cartoons]
And With several swing states poised to play a major role in determining who wins the White House, VP candidates with a ties to purple states should be topping the list.
"Is there somebody who can give you Ohio. Is there somebody who can give you Pennsylvania?" Barbour wonders. "Do you need Rubio to win Florida? Do you need McDonnell to win Virginia? Do you need Scott Walker to win Wisconsin?"
The Mississippi governor says that might be one of the strongest factors weighing on Romney who he says couldn't afford to lose both Ohio and Pennsylvania.
"If either one of these candidates carries Ohio or Pennsylvania, he is probably going to be president," Barbour says.
Barbour adds that Florida Sen. Marco Rubio and New Mexico Gov. Susana Martinez are both strong candidates as well who might be able to bring a few Latino voters into the GOP's tent.
And while Barbour says it is a risky move, some in the past have opted for more of the "Game Change" strategy. [Victorious Gov. Scott Walker Gives Mitt Romney Some Political Advice.]
"Pick somebody who reshuffles the deck," Barbour says. "If you are really down and things are going bad, try to get somebody who gives you a fresh start or wins some big group of people. That is not real likely to happen."
Barbour says that scenario's the least likely for Romney who came right out of the gate as tough competition for the president.
But as careful as a candidate should be in making the decision, at the end of the day, Barbour says Romney's name on the ballot is going to be the one that matters most.
"Certainly people vote more for the top of the ticket, but sure it can make some difference," Barbour says. "And in some states where it is very close, a small difference can be all the difference."