By Jill Disis

NEW YORK (CNNMoney) -- The White House says Kellyanne Conway, a senior adviser to President Trump, has been "counseled" after she promoted Ivanka Trump's fashion line in a television interview.

Conway was speaking from the White House briefing room on Thursday morning when she told Fox News Channel that people should "go buy Ivanka's stuff."

A day earlier, the president had attacked Nordstrom department stores for dropping his daughter's line of clothing and accessories.

Ethics lawyers and Democratic lawmakers quickly called for investigations into Conway's endorsement, and suggested or said outright that she had violated government ethics law.

White House press secretary Sean Spicer told reporters that Conway has been "counseled on that subject, and that's it." He did not elaborate.

On Fox News, an interviewer raised the subject of Ivanka Trump. Conway praised her as a "very successful businesswoman" and a "champion for women empowerment," and offered statistics about how many stores sell her merchandise.

"Go buy Ivanka's stuff, is what I would tell you," Conway said. "It's a wonderful line. I own some of it. I fully -- I'm going to just, I'm going to give a free commercial here: Go buy it today, everybody. You can find it online."

Federal law says that public employees may not use their positions "for the endorsement of any product, service or enterprise, or for the private gain of friends, relatives, or persons with whom the employee is affiliated in a nongovernmental capacity."

Larry Noble, the general counsel of the Campaign Legal Center, a nonpartisan organization of election law experts, said that in his opinion, Conway "may have violated the law."

The White House did not immediately respond to a request for comment.

An ethics group, Citizens for Responsibility and Ethics in Washington, asked for the Office of Government Ethics and the White House counsel's office to look into the "apparent violation of law" and to "take any necessary discipline against her."

The Office of Government Ethics advises executive branch officials on how to avoid conflicts of interest. Its director harshly criticized Trump last month for his decision to not divest ownership of his business interests.

The office did not return a request for comment, but it said in a series of tweets that it was fielding an "extraordinary volume" of phone calls, emails and web traffic from citizens in response to "recent events."

The ethics office stressed that it does not have enforcement power, but it said that it refers possible ethics violations to Congress, the FBI and other agencies.

Representative Elijah Cummings of Maryland, the top Democrat on the House Oversight Committee, asked the committee chair, Republican Jason Chaffetz of Utah, to review Conway's comments for "potential disciplinary action."

"This appears to be a textbook violation of government ethics laws and regulations enacted to prevent the abuse of an employee's government position," he wrote. Chaffetz did not immediately respond to a request for comment.

Richard Painter, who served as chief ethics lawyer in the George W. Bush administration, said he would not address whether any White House official was violating the law.

But he said public officials, when giving public speeches or TV interviews in an official capacity, may not promote the products of "a particular private business belonging to the employee's own family, the President's family, a friend, a campaign contributor or anyone else."

"That was strictly forbidden in the Bush administration because it is illegal," he said.

Stan Brand, a former chief legal officer for the House of Representatives, said that Conway's endorsement appeared to be "technically a violation."

He suggested it was doubtful that any law enforcement official would pursue "a single statement like this," but he said "a pattern or practice of such conduct could become a problem."

Nordstrom said last week that it would no longer carry Ivanka Trump's line of clothing and accessories because of "brand performance." An online campaign called #GrabYourWallet has encouraged shoppers to boycott Ivanka Trump merchandise.

In addition, the company that owns TJ Maxx and Marshalls said that it recently sent a memo to workers instructing them not to highlight the Ivanka Trump brand in stores. It did not provide a reason for those instructions.

And the Belk department store chain said it plans to pull Ivanka Trump products from its website, but will continue to offer them in stores. Belk said the decision was a response to customer feedback.

On Wednesday, Trump tore into Nordstrom for mistreating his daughter.

"My daughter Ivanka has been treated so unfairly by @Nordstrom. She is a great person -- always pushing me to do the right thing! Terrible!" he tweeted.

The message was retweeted by the official presidential Twitter account, @POTUS, and raised eyebrows among ethics lawyers.

Noble said the president's tweet was "totally out of line."

"He should not be promoting his daughter's line, he should not be attacking a company that has business dealings with his daughter, and it just shows the massive amount of problems we have with his business holdings and his family's business holdings," Noble said Wednesday.

The rules on endorsements by public officials exempt the president and vice president.

Sean Spicer, the White House press secretary, defended the president's use of the @POTUS handle to discuss his daughter's business.

"This was less about his family's business and an attack on his daughter," he told reporters on Wednesday.

--CNNMoney's Cristina Alesci contributed to this report.

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