Progressive luminary Howard Dean on Sunday warned disenchanted liberals not to push for a primary challenge against President Barack Obama in 2012, arguing it would be "a bad thing" for the Democratic Party and for America.

"I don't think he's going to face an opponent in the Democratic primary," Dean said on CBS' "Face the Nation." "I think that would be a bad thing for the country and I think that would be a bad thing for the Democratic Party."

A former Vermont governor and former Democratic National Committee chair, Dean is a trusted voice among liberals who view Obama as ideologically out of sync with them and too willing to compromise on core progressive priorities.

In the wake of widespread losses in the 2010 midterm elections, journalists and pundits are pontificating Obama's fate in 2012, which may be influenced by his still-supportive but less enthusiastic Democratic base.

As a recent McClatchy poll points to declining Democratic support for Obama, behind the scenes liberal activists are weighing the prospect of supporting a more progressive alternative to Obama in the 2012 primary, although even some of Obama's most avid critics are acutely aware that doing so could backfire.

Dean summarized that viewpoint. "The history of people running against presidents in their own party is the challenger loses and then the president is weakened and loses," he said.

It's rare for a sitting president to be challenged from within his own party during a re-election bid. But a much-discussed example is Sen. Ted Kennedy's failed primary challenge to Democratic President Jimmy Carter in 1980, which led to intra-party fighting and cleared the way for Ronald Reagan's victory.

For some activists, part of the goal would be to raise issues and influence the discourse. Nevertheless, the Obama administration's actions over the next two years will play a role in determining whether or not -- and how forcefully -- liberals push to challenge him in 2012.

"The president has done some things that I think are terrific," Dean said. "[His tax cuts deal with Republicans] is not one of them, but I think that he will not get an opponent."