By AMANDA SEITZ, Associated Press

WASHINGTON (AP) — Dr. Mehmet Oz, President Donald Trump’s pick to lead the Centers for Medicare and Medicaid Services, will testify before the Senate Finance Committee on Friday morning.

The 64-year-old was a respected heart surgeon who turned into a popular TV pitchman. Now he has his sights on overseeing health insurance for about 150 million Americans enrolled in Medicare, Medicaid or Affordable Care Act coverage.

Republicans, who have coalesced around Trump’s nominees for the health agencies, are likely to ask Oz about his plans for Medicare and Medicaid, including the Trump administration’s focus on eliminating fraud from the $1 trillion programs.

Democrats, meanwhile, will question Oz’s tax filings, which they say show he has used a tax code loophole to underpay taxes by thousands of dollars on Medicare, the program he’ll oversee. They will also grill Oz on any cuts he would make to the health insurance coverage as well as comments on his TV show supporting privatized Medicare.

The U.S. Office of Government Ethics has done an “extensive review” of Oz’s finances, spokesman Christopher Krepich said in a statement about Oz’s taxes. He added that the office has indicated “any potential conflicts have been resolved and he is in compliance with the law.”

Oz has hawked everything from supplements to private health insurance plans on his former TV series, “The Dr. Oz Show,” which ran for 13 seasons and helped him amass a fortune.

Oz’s net worth is between $98 million and $332 million, according to an analysis of the disclosure, which lists asset values in ranges but does not give precise dollar figures. His most recent disclosure shows he also holds millions of dollars worth of shares in health insurance, fertility, pharmaceutical and vitamin companies. He has promised to divest from dozens of companies that would pose conflicts for him as the CMS administrator.

In the job, he could wield significant power over most health companies operating in the U.S. because he can make decisions about who and what are covered by Medicare and Medicaid.

Oz’s hearing comes as the Trump administration seeks to finalize leadership posts for the nation’s top health agencies. On Thursday, Senate committees voted to advance the nominations of Marty Makary, poised to lead the Food and Drug Administration, and Jay Bhattacharya, set to helm the National Institutes for Health, for a full Senate vote. The nomination of Dave Weldon to the Centers for Disease Control and Prevention was abruptly withdrawn Thursday.

Those men have all leaned into Robert F. Kennedy Jr. ‘s call to “Make America Healthy Again,” a controversial effort to redesign the nation’s food supply, reject vaccine mandates and cast doubt on some long-established scientific research.

“Americans need better research on healthy lifestyle choices from unbiased scientists,” Oz wrote late last year in a social media post praising Kennedy’s nomination to be the nation’s health secretary.

This isn’t Oz’s first time testifying before senators. In 2014, several senators scolded him during a hearing about the questionable weight loss products he hawked on his television show.

AP Health Writer Tom Murphy contributed to this report from Indianapolis.