Andrew Wheeler, President Trump’s pick for EPA administrator, clashed with Vermont Sen. Bernie Sanders on Wednesday over whether climate change is a global crisis during a contentious confirmation hearing that saw environmental protesters ejected from the room.

Wheeler told Sanders he believes “climate change is real” and “man has an impact on it.” But the liberal senator, gearing up for a possible 2020 presidential campaign, repeatedly pressed the nominee to call it a “global crisis,” something Wheeler declined to do.

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“Do you agree with the scientific community that climate change is a global crisis that must be addressed in an aggressive way?” Sanders asked.

“I would not call it the greatest crisis, no sir,” Wheeler replied. “I consider it a huge issue that has to be addressed globally.”

During the hearing before the Senate Environment and Public Works Committee, Sanders slammed Trump for past comments referring to climate change as a hoax. Asked if he agrees, Wheeler replied, “I have not used the ‘hoax’ word myself.”

Sanders went on to criticize Wheeler for not bringing up climate change himself during his opening remarks.

“Now how does it happen that the nominee to be head of the Environmental Protection Agency does not mention the words climate change at the time when the scientific community thinks that climate change is the great environmental crisis facing this planet?” Sanders asked.

Wheeler replied that the EPA is moving forward with plans to reduce carbon dioxide and address greenhouse gases.

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“We are implementing the laws that Congress has passed,” he said.

The president in November named Wheeler, who has served as deputy and acting administrator, to replace scandal-plagued Scott Pruitt, who resigned over the summer. He was confirmed by the Senate as deputy administrator in April.

Wyoming Republican Sen. John Barrasso, the chairman of the committee, said Wheeler “has done an outstanding job leading the EPA these past six months,” adding that “the agency has taken a number of significant actions to protect our nation’s environment while also supporting economic growth.”

Democratic Sen. Tom Carper, the top Democrat on the committee, complimented Wheeler for "engaging more frequently and substantively” than Pruitt but added that "upon examination, Mr. Wheeler’s environmental policies appear to be almost as extreme as his predecessor.” Carper cited rollbacks in car mileage standards and toxic mercury emissions under Wheeler as examples of unsafe deregulation, saying they went beyond what industries themselves wanted.

Outside the hearing room, some protesters were seen being arrested by Capitol Hill police. (Caroline McKee/Fox News)

Wheeler’s opening statement was interrupted Wednesday by protesters, with one demonstrator yelling, "Shut down Wheeler! Not the EPA!"

During his remarks, Wheeler said protecting human health and the environment were his most important responsibility. He also boasted of the Trump administration's regulatory rollbacks at the EPA, saying the administration has finished 33 major deregulatory actions saving Americans almost $2 billion.

Outside the hearing room, six protesters were arrested after being warned by Capitol Hill police.

Fox News’ Caroline McKee, Chad Pergram and The Associated Press contributed to this report.