The list of potential vice presidential picks for presumed Republican nominee Mitt Romney is narrowing dramatically. First, Marco Rubio begged off, stating he wouldn’t be on the ticket; now, South Carolina Governor and Mitt Romney backer Nikki Haley is saying she wants no part of the ticket. “I’d say, ‘Thank you, but no,’” she told ABC News:

I made a promise to the people of this state. And I think that promise matters. And I intend to keep it. This is what I want to do … So do I want to think about anything in the future? No.

Haley did defend the GOP against liberal charges that there is some sort of conservative “war on women” in the works. “The public likes to think that women only care about contraception,” said Haley. “We’re so much smarter and broader than that.”

Meanwhile, Romney’s choices seem to be centralizing around a few select candidates: Rep. Paul Ryan (R-WI), Virginia Gov. Bob McDonnell (R-VA), and Sen. Rob Portman (R-OH). Of these, Ryan is likely the best pick – he’s from a swing state, and has solid Republican support. He’s a policy wonk, and he gives the Romney ticket the patina of expertise it will need to compete with Obama’s broad rhetoric. Ryan endorsed Romney this week. Don’t be surprised to see him on the ticket.