White House counselor Kellyanne Conway is hitting back at former Secretary of State John KerryJohn Forbes KerryJohn Kerry: Democratic debate 'was something of a food fight' Kerry responds to Trump accusation he violated Logan Act: 'Another presidential lie' Mellman: Primary elections aren't general elections MORE after he criticized President Trump's decision to pull the U.S. out of the Paris climate agreement.

“Once a politician always a politician,” Conway said Friday on Fox News of Kerry, the Democrats' 2004 nominee for president.

“I think it’s a very disappointing assessment, and it tells you why he lost when he ran for president and why his friend Hillary ClintonHillary Diane Rodham ClintonComey responds to Trump with Mariah Carey gif: 'Why are you so obsessed with me?' Trump dismisses reports of Russian meddling, labels them Democratic 'misinformation campaign' The new American center MORE lost this past time, because people don’t feel in this country like they put America first and the American worker first,” she added.

President Trump announced he would pull the U.S. out of the climate deal Thursday, calling it “unfair at the highest level to the United States.”

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Kerry and the Obama administration played an instrumental role in negotiating the Paris accords. The former Massachusetts senator even signed the deal with his granddaughter sitting on his lap.

Kerry blasted Trump's decision earlier Friday.

“He’s [President Trump] made us an environmental pariah in the world. And I think it is one of the most self-destructive moves I’ve seen by a politician in my lifetime,” Kerry said on MSNBC.