(CNN) - Former President Jimmy Carter took a jab at President Barack Obama and former Secretary of State Hillary Clinton over their handling of Middle East peace negotiations in an interview published Thursday.
Heralding the nation's current top diplomat, John Kerry, the former Democratic President told TIME Magazine he has "great admiration" for Kerry and the two stay in touch frequently through email.
"He has had a very difficult time operating pretty much on his own," Carter said about Kerry's role in the Mideast peace process. "I know from experience that the best way to have the United States be a mediator is for the president himself to be deeply involved."
But in praising Kerry, Carter went on to argue that Clinton – Kerry's predecessor – failed to play a major role in the peace-making process.
"In this occasion, when Secretary Clinton was Secretary of State, she took very little action to bring about peace. It was only John Kerry's coming into office that reinitiated all these very important and crucial issues," Carter said.
TIME noted that the interview was edited for length.
Carter has been known to offer candid assessments of both Republican and Democratic presidents and their administrations, including former President Bill Clinton. Throughout much of Clinton's presidency, Carter was a Democratic agitator. He embarked on his own foreign policy projects, at times at direct odds with the White House.
The idea that Clinton failed to make big achievements during her four years at the State Department is an argument Republicans have latched onto as they prepare for a possible 2016 presidential run by the former first lady and former senator.
"Whether it was acting with the next political campaign in mind or merely following a weak Obama-Hillary foreign policy, Hillary Clinton has very little to show for her four years in the State Department," said Kirsten Kukowski, spokeswoman for the Republican National Committee.
Since leaving the State Department in 2013, Clinton has toured the country on the paid speaking circuit and regularly talks about her four years as the nation's top diplomat. In particular, the former first lady frequently highlights her role in major issues involving Iran, Syria and Libya, as well as steps she took to achieve equality for women and children around the world. She made 16 trips to the Middle East and North Africa.
She's set to release a book in June detailing her time as secretary.
CNN reached out to her spokesman for a response to Carter's comments.
Since succeeding Clinton, Kerry has been active in negotiations for a peace deal between Israel and the Palestinian Authority, visiting the Middle East more than a dozen times since taking office last year.
He's also been highly involved in a multi-country agreement with Iran to reduce its stockpile of highly enriched uranium and allow inspectors into some of its facilities.
But Kerry hasn't been immune to criticism. At a Senate hearing just this week, Republican members of the Foreign Relations Committee–which he used to chair–criticized Kerry over the Obama administration's Syria and Ukraine policies.
CNN Political Producer Rachel Streitfeld contributed to this report.