Scott Gottlieb and Pfizer surely knew critics would challenge the former FDA commissioner’s decision to join the pharma giant’s board—less than three months after his departure from the agency, no less.

And at least one high-profile lawmaker is doing just that, as Sen. Elizabeth Warren called on Gottlieb to reconsider.

The move “smacks of corruption,” Warren wrote in a letter following the announcement. Gottlieb will join a company that has “billions of dollars at stake in the decisions made by the agency you used to head and the employees you used to lead,” Warren wrote.

Such a fast move from government to industry “makes the American people rightfully cynical and distrustful about whether high-level Trump Administration officials are working for them, or for their future corporate employers,” she added. 

The move could prove to be lucrative for Gottlieb as Pfizer compensates its board members well, Warren pointed out. Last year, the company paid directors $335,000 in cash and stock.

Gottlieb took to CNBC to defend the decision. He said in an interview with the network that he’s “proud” of the relationship. He worked in the life sciences industry before he joined the FDA, and now has returned to similar roles, he added.

“I feel very confident about my record at the agency and the fact that I called balls and strikes and acted in the interest of public health,” Gottlieb said. 

Gottlieb announced his FDA resignation in March and served until the beginning of April. He started with the agency in May 2017. In stepping down, he said he wanted to spend more time with his family.  

At the FDA, he was popular for taking an industry-friendly stance on numerous issues involving innovation and for fighting high drug prices.