Former Environmental Protection Agency Administrator Scott Pruitt, who left the agency as he was under investigation by several federal agencies for questionable expenditures, released his first Senate campaign advertisement, claiming he was "canceled" by the media.

Pruitt held the EPA head role under former President Donald Trump from February 2017 to July 2018 and resigned amid investigations into his alleged spending abuses of taxpayer dollars. Now, Pruitt is seeking to run for Senate to succeed retiring Sen. Jim Inhofe (R-OK) in a crowded Republican primary race.

"Winston Churchill said, 'You got enemies? Good. That means you stood up for something,'" Pruitt said in a new campaign video released Thursday. "As a member of President Trump's Cabinet, I had enemies — New York Times, Washington Post. They think they canceled me. But guess what? I'm back."

Pruitt's first campaign video comes nearly a month after he filed to run for Senate, according to the state's candidate filing database, and just one day after he attended a U.S. Senate forum Wednesday with candidates including state Sen. Nathan Dahm and Luke Holland, Inhofe's chief of staff and preferred successor.

"Joe Biden is undoing the progress we made in the Trump administration. He's hurting America, and something must be done ... that's why I'm running for the United States Senate," Pruitt says in the ad.

At the Senate forum, Pruitt emphasized his experience as Oklahoma's former attorney general and his work during the Trump administration to limit regulations in the petroleum industry.

“It’s hard to invest capital today when the administration tomorrow is, what, criticizing fossil fuels and saying we don’t need fossil fuels for our future?” Pruitt said, according to NonDoc. “It’s hard to take that risk.”

The former EPA head also harped on the 2020 McGirt v. Oklahoma Supreme Court ruling that deemed a significant portion of the state "Indian country" and limited only tribal law enforcement to prosecute crimes on Native American land, arguing the ramifications of the ruling would extend beyond criminal law.

“Anyone who tells you that decision isn’t going to have impact in the state beyond criminal law is just simply not telling the whole story,” Pruitt said, underscoring a top issue among Republican leaders such as Gov. Kevin Stitt and Attorney General John O'Connor, who recently asked the Supreme Court to determine whether state law enforcement can prosecute nontribal people who commit crimes against tribal citizens on Native American land.

Other notable Republican candidates running for Inhofe's seat include 2nd District Rep. Markwayne Mullin, former House Speaker T.W. Shannon, and Alex Gray, who were not in attendance for the hourlong Senate forum. A video played during the forum featured Mullin saying he was in Washington, D.C., to attend a briefing on security measures.

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Pruitt drew as much attention for his policy proposals in the Trump Cabinet as he did for questions of his ethics.

From his early months in office, Pruitt faced questions about alleged spending abuses, including insisting on staying in luxury hotels that were costlier than allowed by government standards, first-class travel at taxpayer expense, and alleged cozy relationships with lobbyists, among other conduct.