WASHINGTON — When they won the majority last year, House Democrats promised a barrage of investigations into President Trump and those around him. It now looks more like a continuous bombardment.

This week alone, Democrats on the Judiciary Committee sent 81 document requests seeking information on potential obstruction of justice, abuse of power and corruption in the Trump administration. Three more committees demanded documents and witness interviews related to Mr. Trump’s private communications with President Vladimir V. Putin of Russia. And the Intelligence Committee subjected Michael D. Cohen, once one of the president’s most loyal aides, to his fourth congressional grilling in a little more than a week.

The Democratic investigations will long outlast the special counsel, Robert S. Mueller III, and are already a tangle of targets and witnesses. Speaker Nancy Pelosi of California told reporters on Wednesday that Mr. Trump was in “denial.”

Here is where the investigations stand.

Judiciary Committee

Possible obstruction of justice and abuse of power by the president

The Judiciary Committee has one of the broadest mandates of any in Congress, and its chairman, Representative Jerrold Nadler of New York, intends to use almost every inch.