LONDON – The American ambassador to Britain, Robert Wood Johnson, told multiple colleagues in February 2018 that President Donald Trump had asked him to see whether the British government could help steer the world-famous and lucrative British Open golf tournament to the Trump Turnberry resort in Scotland, according to three people with knowledge of the episode.

The ambassador’s deputy, Lewis Lukens, advised him not to do it, warning that it would be an unethical use of the presidency for private gain, these people said. But Johnson apparently felt pressured to try. A few weeks later, he raised the idea of Turnberry playing host to the Open with the secretary of state for Scotland, David Mundell.

Mundell said it was “inappropriate” for him to discuss his dealings with Johnson and referred to a British government statement that said Johnson “made no request of Mr. Mundell regarding the British Open or any other sporting event.” The statement did not address whether the ambassador had broached the issue.

Still, the episode left Lukens and other diplomats deeply unsettled. Lukens, who served as the acting ambassador before Johnson arrived in November 2017, e-mailed officials at the State Department to tell them what had happened, colleagues said. A few months later, Johnson forced out Lukens, a career diplomat, shortly before his term was to end.

The White House declined to comment, as did Johnson and the State Department.

Although Trump, as president, is exempt from a federal conflict-of-interest law that makes it a criminal offense to take part in “government matters that will affect your own personal financial interest,” the Constitution prohibits federal officials from accepting gifts, or “emoluments,” from foreign governments.

Experts on government ethics pointed to one potential violation of the emoluments clause that still may have been triggered by the president’s actions: The British or Scottish governments would most likely have to pay for security at the tournament, an event that would profit Trump.

It was not the first time the president tried to steer business to one of his properties. Last year, the White House chose the Trump National Doral resort in Miami as the site of a Group of Seven meeting. Trump backed off after it ignited a political storm.

Trump also urged Vice President Mike Pence to stay at his family’s golf resort in Doonbeg, Ireland, last year even though the vice president’s official business was on the other side of the country. And Trump has visited his family-owned golf courses more than 275 times since he took office, bringing reporters with him each time, ensuring that the resorts get news coverage.

The Trump International Hotel in Washington has done a brisk trade in guests, foreign and domestic, who are in town to lobby the federal government. Turnberry drew attention when the Pentagon acknowledged it had been sending troops to the resort while they were on overnight layovers at Glasgow Prestwick Airport.

Trump and his children have struggled for more than a decade to attract professional golf tournaments to the family’s 16 golf courses.

This has been particularly important for the two Trump resorts in Scotland and one in Ireland, which have been losing money under Donald Trump’s ownership. Trump himself was intensely involved in promoting them before he was elected.

But the campaign to recruit tournaments has been complicated by Trump’s political ascent. Executives who run the Scottish Open, for example, said in 2017 that they would most likely not hold the tournament at the Trump family’s Aberdeen golf resort, even after direct appeals by Donald Trump.

Beyond the legal and ethical red flags, asking for such a favor from his host country would put Johnson in an untenable position as the emissary of the United States.

“It is diplomatic malpractice because once you do that, you put yourself in a compromised position,” said Norman L. Eisen, who served as President Barack Obama’s special counsel for ethics and later as his ambassador to the Czech Republic. “They can always say, ‘Remember that time when you made that suggestion.’ No experienced diplomat would do that.”