Inside Trump Inc.: The president's known holdings, in one graphic

President Donald Trump faces another lawsuit, this time from the attorneys general of Maryland and the District of Columbia, over an alleged Constitutional conflict of interest stemming from his ownership in a Washington, D.C. hotel.

The suit alleges that Trump hasn't gone far enough to separate himself from his ownership of a luxury Washington hotel that has hosted multiple foreign delegations since he was sworn in as president.

"Foreign governments are spending money there in order to curry favor with the president," Karl Racine, attorney general for the District of Columbia, told reporters Monday. "We are a nation of laws, and no one, including the president of the United States, is above the law."

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

The president's ongoing ethical difficulties result from his refusal to divest himself of a sprawling network of more than 500 properties that he has amassed in more than three decades as a celebrity entrepreneur.

The full scope of Trump's business interests remains unclear. The primary source of information consists of an unaudited filing with the OGE in May 2016 by Trump and other candidates running for the White House. Trump made a similar filling a year earlier.

'Blind trust'

Monday's lawsuit follows a separate legal challenge, filed in January the day Trump took office, citing wider conflicts of interest that include Trump's far-flung international holdings.

Trump and his attorneys brush aside allegations of conflicts. In January, his attorneys laid out the broad outlines of a plan to separate him from the day-to-day operations of his businesses.

The plan included the establishment of a trust to be run by his two sons and a Trump Organization executive. The company said an ethics adviser would clear any new domestic deals, and Trump pledged to donate to the U.S. Treasury any hotel profits generated from foreign governments to avoid the appearance of gifts.

But last month, Trump representatives told NBC News that they weren't tracking all payments from foreign governments.

Trump's divestiture plan had already drawn criticism for not going far enough to head off major ethical conflicts from Walter Shaub Jr., director of the U.S. Office of Government Ethics. The new structure, he said in January, was "meaningless."

"This is not a blind trust — it's not even close. ... His sons are still running the businesses, and, of course, he knows what he owns," Shaub said, upon hearing the details of Trump's plan. "His own attorney said today that he can't 'un- know' that he owns Trump Tower. The same is true of his other holdings."

Monday's lawsuit seeks to shed more light on the extent of Trump's businesses with a subpoena for copies of his tax returns, which the president has repeatedly refused to release.

"If the attorneys general are successful in getting his tax returns subpoenaed, that would be a big problem for the president," Republican strategist Rick Tyler told MSNBC.