(The Hill) — Consumer activist Ralph Nader said Tuesday that he’ll launch an initiative soon to field primary challenges to President Obama in key states.

Nader, who waged two presidential campaigns as a third-party candidate, is working with a group of frustrated Democrats who are hoping to turn up the heat on Obama from the left.

“It’s an initiative to scan the possibilities of people who may run,” Nader said in a phone interview. “My guess is that it’s almost 100 percent sure there’s going to be a primary challenge to Obama from somebody or somebodies — plural — in some states.”

Nader’s effort follows comments over the weekend by Sen. Bernie Sanders (Vt.), a liberal independent who caucuses with Democrats, that it would be a “good idea” for Obama to face a primary challenge in 2012.