Hillary Clinton has often found herself on the defensive when asked to name her accomplishments as secretary of state, and Barack Obama isn’t making things any easier. Asked during an interview Sunday to name the “worst mistake” of his presidency, Obama said it was failing to anticipate the fallout from toppling Libyan dictator Muammar Gaddafi in 2011—one of the policies cited by Clinton as one of her chief accomplishments when she headed the State Department.

“Probably failing to plan for the day after, what I think was the right thing to do, in intervening in Libya,” Obama told Fox’s Chris Wallace.

It wasn’t the first time the president admitted his administration had failed its mission in the now war-torn North African country. In a recent profile in The Atlantic, Obama called Libya “a mess,” blaming, in part, the European coalition, led by British prime minister David Cameron, for not doing enough to re-stabilize the country after toppling Gaddafi. But he also blamed his own analysts for failing to understand the deep, pre-existing tribal divisions in Libya, factions that regained strength without the presence of an authoritarian regime, turning the country into a hotbed of religious extremism and a breeding ground for ISIS. (Privately, Atlantic interviewer Jeffrey Goldberg reported, Obama called the Libya situation a “shit show” that proved the U.S. had no business attempting to govern the Middle East and North Africa.)

Obama’s comments highlight a growing divide with Clinton as she seeks to win the Democratic presidential nomination. As secretary of state, Clinton was one of the strongest proponents of the U.S. intervention in the Libyan civil war against Gadhafi; according to the New York Times, the decision to commit military assets to ending the dictator’s 42-year-old regime was “arguably her moment of greatest influence as secretary of state.” While Obama has now pointed to that decision multiple times as one of his biggest regrets, he has also used the same logic to defend his reticence to intervene in Syria, where Clinton has urged a more militaristic approach, including a no-fly zone.

Obama has repeatedly said that Clinton would make a great president, and behind the scenes, has urged Democratic donors to coalesce behind her White House bid. While he may have put her Libya boosterism in a negative light during his Fox interview Sunday, Obama also praised her tenure and suggested that the emails she sent and received over a private server weren’t a direct threat to national security. Still, Obama admitted that the practice itself was not secure, and that he would not exert any political influence over the investigation into her emails.