I nominate Michael Moore.

(The Hill) — One of the Senate’s liberal leaders said Wednesday that it would be beneficial for President Obama to face a primary challenger from the left in 2012.

Sen. Bernie Sanders (I-Vt.), who has criticized the president for — among other things — brokering a tax deal with Republicans, said that it is worthwhile to have a wide array of voices in the campaign.

“If a progressive Democrat were to run, I think it would enliven the debate,” he said during an interview on WNYC Radio. “They are free to do that.”

Sanders’s comments could revive talk of a primary challenge to Obama; many observers speculated that could happen after Democrats took a beating in the midterm elections, making the president look vulnerable for reelection in 2012.