Democrats on Wednesday asked the Environmental Protection Agency’s inspector general to investigate how Administrator Scott Pruitt has obtained a “blanket waiver” to fly first class.

The EPA on Tuesday said Pruitt is pre-approved to fly first-class whenever he wants because of security concerns.

“Due to security reasons, he has a blanket waiver to buy business or first class,” spokesman Jahan Wilcox said.

Rep. Frank Pallone of New Jersey, the top Democrat on the House Energy and Commerce Committee, and other committee Democrats, are urging the EPA’s inspector general to expand an existing probe of Pruitt’s travel habits to include the circumstances behind the waiver.

The investigation currently covers Pruitt’s frequent travel to and from his home state of Oklahoma and his use of private and government planes.

“Administrator Pruitt’s many first-class flights around the country at taxpayers’ expense raise renewed concerns of secrecy and waste at the Trump EPA,” the lawmakers wrote in a letter Wednesday to the inspector general. “In light of these recent reports, we would expect your ongoing review would determine whether Administrator Pruitt’s ‘blanket waiver’ for premium-class travel is in compliance with all applicable regulations, policies and procedures.”

Pruitt said Tuesday that security-related decisions made by others is prompting him to frequently fly first class or take military flights at taxpayer expense.

“I’m not involved in any of those decisions,” Pruitt said during an interview with the New Hampshire Union Leader. “Those are all made by the [security] detail, the security assessment in addition to the chief of staff.

“Unfortunately, we've had some incidents on travel dating back to when I first started serving in the March-April timeframe,” Pruitt said. “We live in a very toxic environment politically, particularly around issues of the environment,” he said.

Democratic lawmakers want to know if EPA political appointees or career staff were involved in the approval of the waiver. They also want to understand how the EPA determined that flying coach is a security risk and whether other EPA political appointees have been granted exceptions.