The House rushed, fumbled impeachment effort

After the Republican Senate majority shut down the effort to summon John Bolton, Mick Mulvaney, and possibly others, the House Democratic leadership suggested the House could subpoena them to provide the same information.
The oversight responsibilities of the Congress are ongoing.
Included in those oversight duties is the right (some would say the obligation) to inquire into the circumstances of a possible presidential order not to release funds for Ukraine that had been approved by Congres