The attorneys general of Maryland and Washington, D.C., plan to file a “major lawsuit” against President Donald Trump as early as Monday, they said Sunday night.

Maryland Attorney General Brian Frosh and his D.C. counterpart, Karl Racine, didn’t disclose the focus of the litigation, which they said in a statement they would formally announce Monday afternoon.

The Washington Post reported that the lawsuit would allege that Trump has violated constitutional anti-corruption restrictions by accepting payments and benefits from foreign governments since he became president.

No further details were immediately available.