Fox News’ decision to suspend paid contributors Rick Santorum and Newt Gingrich as they weigh presidential ambitions is a judgment call on who is really seriously thinking about it.

That’s why Sarah Palin and Mike Huckabee will continue appearing on the network.

Dianne Brandi, the network’s exec VP of legal and business affairs, tells the Los Angeles Times, “As soon as each of them shows some serious intention to form an exploratory committee, we would take the same action. Huckabee is on a book tour, so I think his present intention is to sell books.”

As for Palin, “She hasn’t yet shown a serious intention to form an exploratory committee.”

All four candidates have been among the names bandied about as possible contenders for months now, much to the consternation of competitors to Fox News and to critics who complain that they’ve essentially been able to boost their profiles on the network without formally declaring.

Santorum says he wasn’t asked whether he was running or not. Perhaps more than any other candidate, he’s gained from his appearances on Fox News, as it has kept his name out there.