Rep. Brian Mast, R-Fla., said Special Presidential Envoy for Climate (SPEC) John Kerry is operating under the "cloak of zero supervision" following a contentious budget hearing Thursday. 

Mast, the chairman of the House Foreign Affairs Subcommittee on Oversight and Accountability, opened Thursday’s hearing by making the case that Kerry, in his newly created position in the Biden administration, has "largely managed to avoid any real oversight or accountability in that position."

Mast told Fox News Digital in an interview following the hearing that Kerry’s office is illegitimate and that he is "working globally under the cloak of zero supervision."

"There is no clarity about who he works for, who he answers to, what he's doing, and that's not accountable to the American taxpayer when he is undertaking policies that allow for those trying to rise up against us to thrive and that throttle the United States of America back," he said.

Subcommittee Chairman Rep. Brian Mast (R-FL)

Subcommittee Chairman Rep. Brian Mast points to an organizational chart of John Kerry's climate office during a hearing at the U.S. Capitol on July 13, 2023. (Alex Wong/Getty Images)

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"They don't have a website, they don't have a landing page, they don't have an ‘About Me’ section for what they do," he continued. "They don't have the lists of the hierarchy of their office. They have no information about them whatsoever. And so that's the problem. We can speculate on what they do, but nobody actually knows what they're doing."

Kerry is traveling to China later this month to restart climate negotiations with his Chinese counterparts, which stalled last year in response to former House Speaker Nancy Pelosi's, D-Calif., high-profile trip to Taiwan. 

John Kerry (L) and Rep. Brian Mast (R-FL) (R)

Special Presidential Envoy for Climate John Kerry extends his hand to Rep. Brian Mast prior to a hearing before the Subcommittee on Oversight and Accountability of the House Committee on Foreign Affairs at the U.S. Capitol on July 13, 2023. (Alex Wong/Getty Images)

Shortly after taking office in 2021, President Biden appointed Kerry to the climate envoy position, which hadn't existed before, didn't require Senate approval, and gives him a spot on the president's Cabinet and National Security Council. The climate office is housed at the State Department and has an estimated $13.9 million annual budget with approval for 45 staff members.

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John Kerry

John Kerry testifies during the House hearing titled "The State Department's Climate Agenda: A Budget Overview by the Special Presidential Envoy for Climate" at the Capitol on Thursday, July 13, 2023. (Tom Williams/CQ-Roll Call, Inc via Getty Images)

Despite the high-level role leading the Biden administration's global climate strategy, Kerry's office has been tight-lipped about its internal operations and staff members, sparking criticism from Republicans.

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Mast told Fox News Digital that "there will be a zeroing out of his office moving forward in the appropriations."

"We want to defund his office. We will," he said.

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Kerry's office did not immediately respond to Fox News Digital's request for comment.

Fox News’ Thomas Catenacci contributed to this report.