A spokesman for the House Judiciary Committee declined to comment on the committee’s interest in Ms. Trump. But Mr. Nadler has said that the 81 requests were only the first tranche and that requests to others, including Ms. Trump, could “quite conceivably” follow.
The characters working behind the scenes on the document requests also provide a hint of what the Judiciary Committee is looking for. In February, House Democrats retained Norman L. Eisen, a litigator and prominent Trump critic, to begin its inquiries into the president. Mr. Eisen, who played a large role in overseeing the document requests, has also been vocal about potential emoluments clause violations from the president and his family. In December 2016, for instance, he was an author of a report for the Brookings Institution, “The Emoluments Clause: Its text, meaning, and application to Donald J. Trump.”
Ms. Trump and her husband, Jared Kushner, never completely divested from their companies even after taking top White House positions. Their income in 2017, from various investments they remained involved in through vehicles and trusts, was $82 million to $222 million, according to their ethics disclosures. In 2017, Ms. Trump earned more than $5 million from her namesake fashion brand, according to financial disclosures.
In July 2018, Ms. Trump shut down her fashion brand, amid concerns that the family was profiting from the presidency. But she has continued to seek trademarks in China to avoid competitors from profiting off her name, according to a spokeswoman.
House Democrats appear to be looking to see if she leveraged her role in government to profit for herself.
Among those asked to produce documents that could show foreign-government involvement with Ms. Trump are George Nader, the Lebanese-American businessman who is cooperating with the special counsel’s inquiry; Erik Prince, the founder of the security contractor formerly known as Blackwater; Matthew Calamari, the former Trump bodyguard turned businessman; and Hope Hicks, a former White House communications director.
Others were Corey Lewandowski, the former Trump campaign manager; Michael T. Flynn, the former national security adviser, and Allen Weisselberg, the chief financial officer of the Trump Organization.
Sarah Huckabee Sanders, the White House press secretary, did not respond to a request for comment.
Abbe Lowell, a lawyer for Mr. Kushner, declined to comment.