The headline: "Nikki Haley: I Wouldn't Accept the Vice Presidential Nomination." It reminds the amateur historian of some other headlines.
February 2, 2004:
Asked how he would respond if party leaders implored him to take the second spot on the Democratic ticket to his Senate colleague from Massachusetts, [John] Edwards told CBS television: "I will say no."
August 19, 2008:
ABC News, was among those on a stakeout at Mr. Biden’s home in Wilmington, Del., and as he climbed into the driver’s seat of a white, very serious pickup truck, the casually dressed senator seemed to peek out the driver’s side window to give a little statement to the cameras gathered: “Hey guys, I’m not the guy. See ya.”
Haley is playing a game here; she can spin superficial national buzz (a USA Today cover this week!), but South Carolina Republicans laugh themselves red-eyed when you ask whether she could survive a real vetting. But the other people who "rule out" a VP nod are doing no such thing. That's not how this works. They take the softball and they pick a direction to hit it in. Say you're mulling it if you need that buzz; "rule it out" if you want a different sort of buzz.