The White House withdrew the nomination of President Donald Trump’s pick for the Centers for Disease Control and Prevention (CDC) director, David Weldon, on Wednesday night, the day before his confirmation hearing was scheduled.

After the withdrawal, Weldon, a medical doctor and former congressman from Florida, released a lengthy statement explaining why he believes he was withdrawn, suggesting that opposition from senators, including Sen. Susan Collins (R-Maine), and his past criticism of large pharmaceutical companies were to blame.

“Twelve hours before my scheduled confirmation hearing in the Senate, I received a phone call from my assistant at the White House informing me that my nomination to be CDC Director was being withdrawn because there were not enough votes to get me confirmed,” said Weldon.

“Bobbie [Department of Health and Human Services Director Robert Kenedy Jr.] told me that earlier that morning he had had breakfast with Republican Senator Susan Collins of Maine who said she now had reservations about and was considering voting no,” he continued.

He outlined a strange series of events in which he met in person with Sen. Collins two weeks ago, at which time she expressed no reservations about his confirmation, he said. However, following that meeting, Weldon met with Collins’ staff on Tuesday and found them extremely hostile.

Weldon stated that Collins’ staff accused him of being anti-vaccine over his isolated concerns about specific vaccines and ingredients, despite his objections that, as a practicing medical doctor, he administers literally hundreds of vaccines every year. ABC News quoted other Senate committee staffers as saying Collins’ staff had not been hostile, but rather insistent on getting questions answered.

Weldon also believed that Sen. Bill Cassidy (R-La.), chair of the Committee on Health, Education, Labor, and Pensions, was set to oppose him because he had previously expressed concerns over the effects of certain vaccines on children.

In addition to Collins and Cassidy, Weldon blamed “big Pharma” for his nomination getting pulled, suggesting that they, along with the CDC, were afraid that he would expose corruption in studies such as those claiming that there are no harms from mercury in vaccines.

He also pointed to his work during his time in Congress to ban a neurotoxic preservative, thimerosal, from use in vaccines—an effort that was eventually successful after years.

“The concern of many is that big Pharma was behind this which is probably true. They are hands-down the most powerful lobbying organization in Washington DC giving millions to politicians on both sides of the aisle,” said Weldon.

“I really wanted to try to make the CDC a better, more respected agency and killing my nomination may have the opposite effect,” he added.

In his statement, Weldon outlined the story of a British doctor who discovered negative effects of a measles vaccine and had his medical license revoked after he published his findings. Weldon claimed that when the CDC was tasked with recreating the doctor’s research for the U.S., they did it improperly and avoided finding any negative effects that could call current vaccine practices into question.

“Clearly, big Pharma didn’t want me in the CDC investigating any of this,” Weldon wrote.

President Trump has not yet announced an alternative pick for the CDC director.