"However, the unrelenting attacks on me personally, my family, are unprecedented and have taken a sizable toll on all of us." While Pruitt was a key figure in Trump's campaign to roll back environmental regulations, he increasingly became seen as a liability in an administration that has seen two Cabinet members fired over ethical lapses and several more accused of wasting taxpayer dollars. The EPA administrator also reportedly alienated colleagues by positioning himself to take over as U.S. attorney general if the frequently embattled head of the Justice Department, Jeff Sessions, stepped down or was fired. Rather, it was Pruitt who became the latest deputy to exit a Cabinet known for its revolving door.

Lightning rod from the start

Pruitt became a lightning rod from the moment Trump nominated him. The Oklahoman rose to prominence as the state's attorney general, where he developed close ties to the energy industry and sued the EPA more than a dozen times. Some corners of industry saw Pruitt as a welcome reprieve from President Barack Obama’s EPA chiefs, who implemented tough new regulations meant to curb pollutants and mitigate the impacts of climate change. As EPA administrator, Pruitt made the case that the agency's primary responsibility is to offer certainty to the energy companies, automakers and other business interests it regulates. He sidelined agency scientists, sought to ease environmental rules and encouraged staff to think of the companies it regulates as its customers. He stood with the president on issues that divided the administration, like pulling the United States out of the Paris climate agreement.

Early in his tenure, he caused an uproar when he said in an interview on CNBC's "Squawk Box" that carbon dioxide emissions from human activity are not the primary cause of climate change. That view contradicts the findings of most climate scientists and the long-standing conclusion of the EPA itself. That made Pruitt a constant foil to Democratic lawmakers and environmentalists, but he soon became notorious for something else: spending taxpayer funds on questionable expenses.

Spending under scrutiny

Pruitt came under scrutiny last year for his frequent travel, sometimes in first class, to his home state. The EPA's inspector general opened an investigation into the matter in August. Reports then surfaced that EPA had installed a custom-made soundproof phone booth in Pruitt's office at a cost of $43,000 to taxpayers. That sparked several investigations, with the Government Accountability Office concluding in April that EPA violated federal laws by approving the expenditure without congressional approval.

Pruitt’s travel habits came back into focus earlier this year as reports showed the EPA chief and staffers had spent at least $90,000 on travel in just a few days in January, including for first-class airfare. The EPA defended Pruitt's pricey itineraries, saying his security detail had ordered him to travel first class due to several threats against the administrator and unspecified incidents during previous trips. Nevertheless, the Republican chair of the House Oversight Committee, Trey Gowdy, opened an investigation into Pruitt's spending. It has since surfaced that Pruitt himself requested round-the-clock protection, which has run up EPA's security costs far beyond what it incurred under past administrators.

Condo controversy opens the floodgates

Soon after, reports surfaced that Pruitt had an arrangement for part of 2017 to pay just $50 a night for an apartment on Capitol Hill owned by the wife of a prominent energy lobbyist. Pruitt was charged only for nights he occupied the space. An EPA watchdog determined Pruitt paid a fair market rate, but later clarified that the review was based on the terms of the lease and an analysis of similar per-night accommodations in the area. The EPA's designated agency ethics official, Kevin Minoli, said he did not have enough facts to answer questions that had arisen about whether Pruitt had stuck to the terms of the lease. Just days after the first news reports on the condo surfaced, the White House announced it was looking into the accommodations. Around the same time, The Atlantic reported that EPA had orchestrated pay raises worth tens of thousands of dollars for two of Pruitt’s close aides after the White House had rejected the salary change.

Two days later, The New York Times reported that several EPA officials had been reassigned or demoted after questioning Pruitt or refusing to sign off on pricey expenses. One of the staffers, former Trump campaign aide Kevin Chmielewski, ultimately detailed a litany of allegations against Pruitt in interviews with congressional Democrats. From then on, the news flow was almost constant. Pruitt came under fire for tasking aides and security staff with performing personal chores: searching for housing, fetching his dry cleaning and inquiring about purchasing a used mattress from Trump International Tower in Washington. Staff were also roped into searching for employment opportunities for the administrator's wife, Marlyn Pruitt. In one notable instance, an aide contacted Chick-fil-A to start the process of securing a branch of the fast-food chain for the Pruitt family. The steady drip dogged Pruitt until his final days. CNN reported on Tuesday that EPA maintained secret calendars to hide meetings with industry executives that might stir criticism. And just hours before Trump announced Pruitt's resignation, The New York Times revealed allegations that EPA fired a senior scheduler who questioned the agency's habit of retroactively deleting sensitive meetings from Pruitt's calendar. Amid the flurry of controversy, several top aides have departed. They include Pruitt's controversial head of security; a close friend from Oklahoma who oversaw the Superfund program; and EPA's top policy, communications and scheduling aides. In congressional hearings and public comments, Pruitt largely placed the blame for the scandals at the feet of career officials and political appointees. Last month, Pruitt's support among Republican lawmakers began to erode after conservative media began to turn on him. Pruitt's political future is now uncertain. He is said to have designs on higher office, including Oklahoma's governorship or one of the state's U.S. Senate seats.

Read Scott Pruitt's resignation letter: