President Trump’s senior aide Kellyanne Conway promoted Ivanka Trump’s products on live TV.
Earlier this month, Nordstrom dropped Ivanka Trump’s clothing line, citing a lack of sales.
However, Kellyanne Conway told Fox News on February 9: “Go buy Ivanka’s stuff.”
Jason Chaffetz, a Republican who heads the oversight committee in Congress, said the promotion was “clearly over the line, unacceptable”.
Federal ethics rules prevent White House employees giving an “endorsement of any product, service or enterprise”.
Jason Chaffetz said the White House should notify the Office of Government Ethics so it could initiate an inquiry. There have been numerous concerns over possible conflicts of interest for White House staff.
He said he and his Democratic counterpart would write to President Donald Trump.
Nordstrom became the fifth retailer to drop the Ivanka Trump clothing line, citing lack of sales.
The move comes amid a boycott of all Trump products, which activists have dubbed #GrabYourWallet, in reference to a 2005 comment Donald Trump made about women’s bodies.
Nordstrom said the decision was based on the brand’s performance, which is what the company repeated on February 8: “Sales of the brand have steadily declined to the point where it didn’t make good business sense for us to continue with the line for now.”
The company added that Ivanka Trump was personally informed of the decision in early January.
Nordstrom shares briefly fell 0.7%, before rising later in the day.
Ivanka Trump does not have a fixed role in the White House, but has been a regular fixture since her father’s inauguration.
Her husband, Jared Kushner, is a key Trump adviser.
Ivanka Trump gave up operating control – but not ownership – of her businesses after her father’s election.