The 30-second television advertisement showed star doctors from a top-notch Manhattan hospital clumsily playing football. From the sidelines, a former standout player for the Giants suggested they should stick to medicine.

The ad promoting NYU Langone Health probably did not rank among this year’s most memorable Super Bowl commercials. But it sure bothered one viewer: a North Carolina congressman.

The lawmaker promptly sent NYU Langone’s chief executive a stern letter, noting that the hospital benefits from federal funds.

“I write today with questions about your stewardship of this money, including our serious concern about your decision to purchase a 30-second advertisement — estimated to cost $8 million — during Super Bowl LIX,” Representative Greg Murphy, a Republican, wrote on Feb. 11. The letter contained a list of pointed questions about NYU Langone’s finances. It is the sort of missive that congressional offices routinely write to gather information for lawmaking or hearings.

NYU Langone is hardly the only New York hospital to spend money on a national advertising campaign, although a Super Bowl ad is unusual. Those commercials speak to the intense competition among the country’s elite medical centers. The congressman’s reaction illustrates that with the promise of being in the spotlight comes peril.

But, it turns out, opinions can change. Eight days after he first contacted the hospital, Representative Murphy wrote a follow-up letter. And that letter could not have been more different. The congressman had gone from critic to booster.

The second letter expressed enthusiastic admiration for NYU Langone’s “world class patient outcomes” and “superb” metrics — such as fewer deaths and shorter hospital stays. “America would be much healthier if all hospitals could report these excellent numbers,” he wrote.

Representative Murphy’s letter stated that he had been left “all-the-more impressed” after recently speaking with NYU Langone’s chief executive, Dr. Robert Grossman. The letter does not indicate whether Dr. Grossman and the congressman had a phone call or met in person.

But just two days before Representative Murphy sent his second letter, a private jet had landed at the sleepy airport in Greenville, N.C., the state’s 12th-largest city, where Representative Murphy lives.

The Bombardier Global 5000 was registered to Invemed Securities, the parent company of Invemed Associates, the investment firm founded by Kenneth G. Langone, the billionaire benefactor of NYU Langone and the chairman of the hospital’s board of directors. Mr. Langone, who is best known for cofounding Home Depot, has given hundreds of millions of dollars to NYU’s hospital system. In return, his name appears on the hospital. And Mr. Langone’s largess allows for free tuition at NYU Grossman School of Medicine.

He is also a major Republican donor, contributing more than $500,000 since 2020 to the National Republican Congressional Committee, which works to elect Republicans to the House of Representatives. He has donated millions more to other Republican organizations, such as the Senate Leadership Fund, a super PAC. Records do not show campaign donations from Mr. Langone to Representative Murphy; there can be delays in reporting contributions.

It is not clear who was on the plane.

A spokesman for NYU Langone, Steve Ritea, declined to answer questions about the hospital’s interactions with the congressman or his staff members. Mr. Ritea also declined to say whether Dr. Grossman, the hospital CEO, flew to see Representative Murphy. Mr. Langone did not respond to requests for comment.

Representative Murphy’s office also declined repeated interview requests on the topic. But his spokesman acknowledged that it might seem “a little confusing” that the tone in Representative Murphy’s letters to Dr. Grossman went from critical to admiring. His spokesman would not share any information about material Dr. Grossman provided or what led the congressman to turn so quickly from critic to booster.

“I don’t have much to add,” the spokesman for the congressman, Alexander Crane, said. “I’d certainly understand that, you know, from A to B to C might seem a little confusing, but basically they had a wonderful private conversation.”

Representative Murphy is a urologist who still regularly treats patients in Greenville. Another doctor at the same office where the congressman sees patients, Dr. Jonathan Hamilton, said he did not know if Mr. Langone or Dr. Grossman came to Greenville to visit Representative Murphy. The incoming chairman of the county’s Republican Party said he hadn’t heard of any such visit either.

The operations manager for the Pitt-Greenville Airport Authority, John Hanna, confirmed that an aircraft with a tail number matching Mr. Langone’s private jet was “here for a short duration.” Flight records, accessible through FlightAware.com, a company that tracks flight information, place that private jet on the ground at Pitt-Greenville Airport for more than two hours on the afternoon of Feb. 17, Presidents’ Day. The plane had flown in from Boca Raton, Fla., and returned there afterward. It appears to have been the only time this year the plane went to Greenville.

Two days later, Representative Murphy released a statement along with his second letter.

“I was left impressed and grateful for the work the institution is doing,” he said.

Representative Murphy’s first letter, on Feb. 11, had posed questions that went beyond how much the Super Bowl ad had cost and how NYU Langone had paid for it. The congressman also asked about the hospital’s overseas investments and why it had sought a “rural” designation that would have increased the subsidies it received. NYU Langone is on Manhattan’s East Side, on land that hasn’t been rural for two centuries.

The letter sought information on whether the health system was exploiting legal loopholes to maximize profit.

In his follow-up letter, on Feb. 19, Representative Murphy wrote that he considered all his “questions thoroughly answered.”

But his office has declined to provide those answers to the public.

Susan C. Beachy contributed research.