A group of four senators led by Sen. Barbara BoxerBarbara BoxerTime is now to address infrastructure needs Tom Steyer testing waters for Calif. gubernatorial bid Another day, another dollar for retirement advice rip-offs MORE (D-Calif.) are calling for the resignation of Environmental Protection Agency Administrator Stephen Johnson, saying that he gave misleading testimony to a Senate committee.

Johnson told the Senate Environment and Public Works Committee in January that he had denied a waiver to California that would have allowed it to enact its own fuel efficiency standards because the state failed to meet necessary criteria. But Boxer and three other senators said Wednesday that Johnson's testimony conflicted with that of an aide, who said that the waiver was denied partly because President Bush opposed it.

Boxer, chairwoman of the Senate Envionment and Public Works Committee, had supported the California standards, which are stricter than federal ones. She again chastised Johnson Tuesday for his decision.

"He has become a secretive and dangerous ally of polluters, and we cannot stand by and allow more damage to be done," she said in a statement. "We have lost all confidence in Stephen Johnson's ability to carry out EPA's mission in accordance with the law. I call on Administrator Johnson to immediately resign his position."

Sens. Amy KlobucharAmy KlobucharDem senator: Trump acting like he's still on ‘The Apprentice’ The next battle in the fight against human trafficking Dems see huge field emerging to take on Trump MORE (D-Minn.), Sheldon WhitehouseSheldon WhitehouseGore wishes Mikulski a happy birthday at 'Inconvenient Sequel' premiere Live coverage: Trump's FBI nominee questioned by senators Committees vie to be first to question Trump Jr. MORE (D-R.I.), and Frank Lautenberg (D-N.J.) joined Boxer's call for Johnson to step down.

The four Democrats and Sen. Bernie SandersBernie SandersSanders keeping door open on 2020 Parliamentarian deals setback to GOP repeal bill OPINION | Hey Dems, Russia won't define 2018, so why not fix your party's problems instead? MORE (I-Vt.) have also asked for a federal probe into whether Johnson's testimony was false or misleading. Download their letter to Attorney General Michael Mukasey here.