Vermont Sen. Bernie Sanders almost challenged former President Barack Obama in 2012 and once chided him for negotiating with Republicans on core issues.

Sanders, who is now running for president, reportedly told several people, including fellow Vermont Sen. Patrick Leahy, that he was frustrated with Obama’s performance in office and seriously considered challenging him in the 2012 Democratic primary. The Atlantic reports Leahy, concerned by Sanders’s comment, relayed the news to Obama’s campaign former campaign manager Jim Messina.

The Obama campaign team “absolutely panicked” at Leahy’s disclosure, as Messina told it, as “every president who has gotten a real primary has lost a general [election].”

Read more at Washington Examiner.