Sen. Elizabeth Warren (D-Mass.) has written a letter to Mehmet Oz, asking him to make a series of commitments to avoid conflicts of interests ahead of his confirmation hearing Friday to lead the Centers for Medicare & Medicaid Services (CMS).

Warren called on Oz to divest from any remaining financial interests in health-related companies to patents that, if confirmed as CMS administrator, he would have the power to influence; to recuse himself from matters that involve his former employers and clients and to pledge not to lobby CMS or join industries that depend on the agency’s work for four years after leaving office.

“If confirmed, you will be expected to steward CMS’s $1.5 trillion budget in the best interest of the over 140 million Americans on Medicare and Medicaid,” Warren wrote in her letter. “Entering this role with financial conflicts of interest would undermine your effectiveness and the effectiveness of the programs you are slated to administer.”

“By making these commitments, you would increase Americans’ trust in your ability to serve the public interest during your time at CMS — rather than the special interests of companies in your network,” she added.

Warren, in her letter, noted Oz has “deep ties to companies that could profit from your [his] decisions at CMS,” pointing to his position serving as managing member or adviser of multiple health care companies and pharmaceutical firms with a financial stake in decisions that CMS will make, including how payment rates are set and whether Medicare and Medicaid cover certain services.

Warren noted that Oz, a former TV personality who launched a failed bid for one of Pennsylvania’s Senate seats, has used his public platform to promote certain drugs that are in the process of seeking expanded CMS coverage approval.

Warren noted that Oz has previously “agreed to divest much of your portfolio and resign from your advisory posts.”

“Still, given your close ties to the industry that you would regulate, if you are confirmed, the public would have reason to question your impartiality and commitment to serving the public’s interest,” she added.