The New York Times reports:
A potentially explosive complaint by a whistle-blower in the intelligence community said to involve President Trump emerged on Thursday as the latest front in a continuing oversight dispute between administration officials and House Democrats.
While the allegation remains shrouded in mystery, it involves at least one instance of Mr. Trump making an unspecified commitment to a foreign leader and includes other actions, according to interviews. At least part of the allegation deals with Ukraine, two people familiar with it said.
The controversy first erupted a week ago, when Representative Adam B. Schiff, Democrat of California and the chairman of the House Intelligence Committee, revealed the existence of the complaint and disclosed that the acting director of national intelligence, Joseph Maguire, had blocked the inspector general from sharing it with Congress, as generally required by law.
In general, the Democrats believe that Trump may have threatened to withhold money from Ukraine unless they help his reelection campaign by investigating Joe Biden. Which, of course, would be illegal.