Must be true. How often is Ralph Nader wrong about anything?

“What [Obama] did this week is just going to energize that effort,” Nader promised in an interview with The Daily Caller. “I would guess that the chances of there being a challenge to Obama in the primary are almost 100 percent.”

The only question, he said, is the stature of that opponent and whether it will be either “an ex-senator or an ex-governor” or “an intellectual leader or an environmental leader.”

In approximately a week and a half there will be “another chapter of this effort,” Nader predicted…

Nader said he doesn’t plan to launch another campaign for president, either as an independent candidate or as a primary challenger to President Obama.

Follow the link for obligatory derision of the tea party as a catspaw of corporate interests. Normally I’d agree with Jay Cost and laugh this off on grounds that “no serious Democratic official would dare challenge Obama,” but the story gives me pause for two reasons. First, Nader sounds like he has someone specific in mind — more than one person, maybe — and that an announcement is in the works. Whether that means he’s found a challenger for Obama on the left and is ready to introduce him publicly or merely that he’s had interest from multiple people, we’ll see, but it suggests this is more than just an aspirational thing.

Second, Cost is right that no serious Democrat would risk his/her status in the party by challenging Obama, but like Bill Kristol says, it doesn’t have to be someone serious. The left knows O will be the nominee. All they want to do is keep him honest so that he doesn’t agree to any more debt deals that make them weep blood in anguish. Kristol:

Surely they’ll produce a primary challenger to their Wall Street coddling, Afghan war prosecuting, drone assassination ordering, and debt ceiling deal-signing occupant of the Oval Office! That opponent might perhaps not be “serious,” but his effort could be attention getting, issue raising, and meaningful for the future. Far be it from me to give advice to the professional left. But it has been a sign of the health and vitality of the right over the last forty years that it could at least produce primary challengers to moderate and establishment Republican officeholders. For the left to roll over totally for Obama, after giving Clinton a pass in 1996, would be a sign of a massive failure of conviction and imagination and nerve.

So, Russ Feingold or Dennis Kucinich, Robert Reich or Paul Krugman: Won’t one of you be willing to raise the progressive banner high? Across the ideological chasm, THE WEEKLY STANDARD will salute you!

Why not? The only risk to Obama from a hard-left liberal running on a lark is that the attacks on him might turn parts of his base against him irretrievably and they’ll stay home in November. But how real is that risk once the Democratic message team gets to work on Mediscaring and framing the GOP nominee as the new Hitler? If Nader and his candidate want to maximize damage to O they’ll skip the primary and run third party, but the base probably won’t go for that given that they still have night sweats about what happened to Gore in 2000. In fact, a challenge from the left in the primary could help Obama by letting him appeal to independents as a “moderate” in the general election. Imagine if (giggle) Krugman jumped in and started screeching about tea-party terrorists and how we need another $5 trillion in stimulus. Obama’s exhausted above-the-fray “adult in the room” crap might start to sound plausible-ish again to centrists.

Exit question: Who’s going to run? (And before you say you-know-who, forget it.) Ideally they want someone with name recognition and gravitas on the left, which I think rules out Kucinich, and someone who has nothing to lose by alienating the Democratic establishment, which probably rules out Feingold. Being good in front of the camera would help a lot too. Are you ready for … Olbermann 2012?