Washington (CNN) Democratic Rep. Alexandria Ocasio-Cortez has "offered more leadership" on climate change "in one day or in one week" than President Donald Trump, former Secretary of State John Kerry said Tuesday.

The comments from Kerry, who served under President Barack Obama, came during a House Oversight Committee hearing on climate change and its impact on national security. Asked by Rep. James Comer, a Kentucky Republican, about the affordability of Ocasio-Cortez's signature Green New Deal proposal, Kerry defended the proposal and criticized Trump's leadership on the issue.

"I think you said that you are not sure of the science (behind climate change studies). But my focus is on how we are going to move forward and, you know, we all have differences on one piece of legislation or another," Kerry said. "But in proposing what she has proposed together with Sen. (Ed) Markey, Congresswoman Ocasio-Cortez has in fact offered more leadership in one day or in one week than President Trump has in his lifetime on this subject."

He continued: "So we're talking about it. And my question is where is your proposal? Did you have any hearings on it in the last few years? Mostly on Benghazi if I recall when I was up here (as secretary)."

According to the committee's website, the hearing was called in order to "examine the threat of climate change to the United States, including national security, and the need for leadership to combat this threat."

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