U.S. President-elect Donald Trump's choice to run the Department of Health and Human Services may have broken the law by making a stock purchase just before he introduced legislation that would have benefited the firm, the Senate's leading Democrat charged on Tuesday.

A confirmation hearing for Tom Price, a Republican congressman and orthopedic surgeon from Georgia, was scheduled for Wednesday before the Senate Health Committee. If confirmed, he would be a key player in carrying out Trump's plans to overhaul Democratic President Barack Obama's signature healthcare law.

CNN reported on Sunday that Price bought between $1,001 and $15,000 worth of shares last March in Zimmer Biomet Holdings Inc (ZBH.N), a medical device manufacturer.

Days later, he introduced legislation in the House of Representatives that would have delayed a regulation that could have ultimately damaged the company, CNN said.

Senator Chuck Schumer of New York, the leader of the Democratic minority in the Senate, called on the Office of Congressional Ethics to investigate whether Price had violated the 2012 Stock Act, a law designed to combat insider trading.

Schumer said Price's Zimmer Biomet purchase may have been in violation of that law. "It may be that this trade was illegal," Schumer said on the Senate floor on Tuesday afternoon.

The Trump transition team said late on Monday that the stock purchase was directed not by Price but by a broker and that the congressman himself did not become aware of the stock buy until well after the legislation was introduced.

The transition team urged CNN to retract the story.

"Any effort to connect the introduction of bipartisan legislation by Dr. Price to any campaign contribution is demonstrably false," said transition spokesman Phil Blando.

Schumer did not sound convinced. "Now they say there's a broker, it's kind of strange that this broker would pick this stock totally independently of him introducing legislation that's so narrow and specific to this company," Schumer told CNN on Tuesday.