With EPA chief Scott Pruitt set to testify before Congress for the first time in months this week as his scandals continue to multiply, Friends of the Earth began airing an ad on "Fox & Friends"—President Donald Trump's favorite TV program—accusing Pruitt of making Washington's "swamp" of corruption "worse than ever" and urging Congress to fire him if the president won't.

"Scott Pruitt is the most corrupt administrator in the history of the EPA," Lukas Ross, climate and energy campaigner at Friends of the Earth, said in a statement on Monday as the ad was set to air. "Since Trump refuses to act, Congress must step up and fire Pruitt."

The new ad campaign, which is running through Thursday, comes as Pruitt is the target of "at least 10 federal investigations" into his conduct as EPA chief, including his "sweetheart" rental from a prominent lobbyist and pricey first-class flights on the taxpayer dime.

"Pruitt has wasted millions of taxpayer dollars on his lavish lifestyle and given special favors to his friends and allies," Ross added. "Americans are sick of it, and we will not let up the pressure until Congress does the right thing and fires Pruitt."