Scott Pruitt is facing mounting pressure to resign from the Environmental Protection Agency amid intensifying scrutiny of his alleged ethical lapses.

On Tuesday, two Republican House members joined Democrats and environmental groups in calling for Pruitt to step down. On Wednesday, White House press secretary Sarah Huckabee Sanders said that the president thinks that hes done a good job, particularly on the deregulation front, but added that we take this seriously and were looking into it. On Thursday, Hogan Gidley, a deputy White House press secretary, said on Fox News that he cant speak to the future of Scott Pruitt.

Pressure escalated Thursday afternoon as two new reports alleged that Pruitt tried to abuse his vehicles emergency sirens to cut through traffic, and that five EPA officials who challenged Pruitts unusually large spending were either reassigned, demoted or forced out.

If Pruitt exits, he will have served the shortest term of any EPA administrator in history, and will be the first forced out since Anne Gorsuch Burford, President Ronald Reagans first EPA administrator, resigned in disgrace in 1983. Burford was EPAs first female administrator (not to mention the mother of Supreme Court Justice Neil Gorsuch), and stepped down after being cited for contempt of Congress for refusing to turn over Superfund records.

Pruitts aggressive attempts to roll back environmental regulations, undermine critical work on climate change and disqualify huge swathes of scientific research in favor of industry-backed science have defined his 14 months at the agency. Yet his future in the Trump administration now hinges on an ongoing White House review of his spending, his use of loopholes to give political appointees unapproved raises, and links to lobbyists who gave him a great deal on a Capitol Hill rental.

To give a sense of just how many questions are now swirling about Pruitt, heres a short list of issues that raise concerns over his leadership as the nations top environmental regulator:

1. His Washington housing arrangement.

At the center of Pruitts ballooning ethics crisis is his $50-a-night sweetheart deal to rent a room in a luxury Capitol Hill townhouse linked to a fossil fuel industry lobbying firm, Williams & Jensen. The EPAs ethics lawyers scrambled to approve the arrangement, but struggled to defend the administrator after news broke that his adult daughter also stayed at the residence. But those EPA lawyers walked back the approval in a Wednesday memo , arguing that they did not have all the necessary information to consider the arrangement. During the time Pruitt stayed at the condominium, Williams & Jensens clients won approval from the EPA for a pipeline-extension project.

2. A shady real estate deal in Oklahoma.

In 2011, Pruitt and his wife, Margaret, bought a property in Tulsa, Oklahoma, days before a court ruled that it had been fraudulently transferred by a Las Vegas developer who was on the hook for a $3.6 million loan default, according to a report the watchdog group Center for Media and Democracy published Thursday in Salon. Pruitt, then Oklahoma attorney general, flipped the property four months later, selling it to a shell company set up by a major campaign donor, Tulsa business magnate and Oklahoma Republican Party finance chair Kevin Hern.

3. Giving unapproved raises.

Pruitt used a loophole in the Safe Drinking Water Act to give two of his longtime aides raises of $56,765 and $28,130 after the White House rejected his request for the salary increases. The law includes a provision that allows the administrator to hire up to 30 people without White House or congressional approval for work related to the law. In a contentious Fox News interview on Wednesday, Pruitt insisted the action was taken without his knowledge, and said he didnt know who made the decision. But the law dictates that the administrator must approve the hires, calling his exasperated statements on Trumps favorite cable channel into question.

4. His first-class travel and his explanation.

Federal regulations dictate that government employees be prudent when making official travel arrangements, and book the least expensive class of travel that meets their needs. Yet Pruitt routinely spent between $1,400 and $4,000 on flights to Boston, New York and Corpus Christi, Texas, according to The Washington Post . He regularly stayed in luxury hotels . His international travel expenses soared into the six figures. In June, a trip to an environmental summit in Italy cost more than $120,000 , while a December trip to Morocco to promote liquefied natural gas a bizarre responsibility for the nations environmental regulator to take on reportedly cost nearly $40,000 with staff. In February, Pruitt defended his first-class airfare, insisting angry members of the public heckled him in economy class.