Ambinder says so and Carl Cameron is reporting it on Fox now. Stand by for updates.

Update: Cameron says it could come tonight or tomorrow. He’s already informed his campaign headquarters, in person.

Update: The website hadn’t been updated in four days. The “Fred File feed” is already offline.

Update: Here’s the official statement via his web guy, Jon Henke:

McLean, VA – Senator Fred Thompson today issued the following statement about his campaign for President:

“Today I have withdrawn my candidacy for President of the United States. I hope that my country and my party have benefited from our having made this effort. Jeri and I will always be grateful for the encouragement and friendship of so many wonderful people.”

Update: The problem in one word: Not laziness but disorganization. Karl’s been doing yeoman’s work at Goldstein’s place lately tracking how Hillary managed to eke out wins against Obama despite the fact that he’s well-funded and light years more charismatic than she is. Read this post and follow the links to the Las Vegas Sun and, especially, to Zak Exley to see what it takes. The media likes sexy/dopey pop-psych narratives about election-eve crying and racial jabs, but organization matters — a lot, a rule Fred always seemed to believe he could ignore by counting on his True Conservative status to carry him through. Again I point you to this Mark Steyn post, or to MM’s tale of how his people couldn’t pull it together to get 500 signatures in Delaware. If the lesson (or one of the lessons) of Ron Paul’s newsletter fiasco was that you can’t trust a guy to manage a country if he can’t manage his own vanity publication, how can you trust a guy who can’t figure out how to get on the ballot in all 50 states?

So I’m chalking it up to disorganization. The alternative, that Bush killed the Reagan coalition dead and left Thompson types inviable no matter how efficiently their machines might run, is simply too terrible to contemplate.

Update: He served up the red meat, says Geraghty, but he didn’t char-grill it.

Update: I fear this news calls for anti-humpbot.

Update: Mitt’s race to lose now in Florida?

Update: I flagged these links after the South Carolina but we’re in obit mode here so let’s bring them back. What’s the legacy of Fred’s campaign? Disappointment and disorganization, yes, but something else too:

The reaction from Marvin Katzen, the McCain supporter who told us earlier in the evening that he was looking for vindication from the 2000 loss to tonight’s win: “Thank God for Fred Thompson.” Katzen credits McCain’s victory to the fact that Thompson split the conservative evangelical vote with Mike Huckabee in Upstate.

“While well behind and tied for third place with Romney, Thompson did make gains,” wrote Thomas Edsall, “and the data suggest that the 6 points Thompson picked up came out of Huckabee’s hide.” Huck’s own people admitted as much. It falls to Romney to finish McCain but Fred can claim a moral victory in having dispatched the demagogue.

Update: If you believe ARG, and you probably shouldn’t, McCain’s lead in Florida is now large enough that picking up Fred’s supporters won’t matter to Mitt.

Update: A wistful eulogy from Spruiell.

Update: Rich Galen, a now former Fred advisor, is pushing his man for veep.