I agree with Kucinich: I think a primary opponent would have the effect of making Obama a stronger progressive candidate. But I'd be very, very surprised if a Democrat decides to run against him:

Congressman Dennis Kucinich will not challenge President Obama for in the 2012 Democratic primaries—“I’m focusing on being re-elected to the House of Representatives”—but he thinks Obama should face a foe for the presidential nomination.

"I think primaries can have the opportunity of raising the issues and make the Democratic candidate a stronger candidate,"Kucinich, who sought the party nod in 2004 and 2008, said Thursday. “I think it’s safe to predict that President Obama will continue to be the nominee of the Democratic primary, but he can be a stronger nominee if he receives a strong challenge in a primary.

”Kucinich won’t speculate on who could, or should, run against Obama, who has disappointed much of the Democratic base with moves to the right on issues ranging from last year’s healthcare debate—in which he abandoned first the single-payer reform he had once backed and then the public option—to tax policy and entitlement reform.

But the Ohio congressman did suggest the issues that he’s like to see raised by another Democrat in the primary states where Obama will begin his re-election campaign.“I’m very interested in making sure that creation of jobs, healthcare for all, protection of Social Security and Medicare, those things are fundamental—and education,” Kucinich explained in a C-SPAN interview. “Those are issues that certainly should be brought up in primaries. And, finally, getting out of Iraq and Afghanistan. We have to stop roaming the world looking for dragons to slay—we’ve things to take care of right here at home.”

Kucinich’s comments echo those of Rabbi Michael Lerner, who wrote last fall, in the aftermath of the midterm election setbacks for Democrats:

“There is a real way to save the Obama presidency: by challenging him in the 2012 presidential primaries with a candidate who would unequivocally commit to a well-defined progressive agenda and contrast it with the Obama administration's policies. Such a candidacy would be pooh-poohed by the media, but if it gathered enough popular support—as is likely given the level of alienation among many who were the backbone of Obama's 2008 success—this campaign would pressure Obama toward much more progressive positions and make him a more viable 2012 candidate. Far from weakening his chances for reelection, this kind of progressive primary challenge could save Obama if he moves in the desired direction. And if he holds firm to his current track, he's a goner anyway.”