Three Democratic House committee chairs issued a strong rebuke Tuesday of Secretary of State Mike Pompeo’s response to their subpoenas for information surrounding Donald Trump’s phone call with Ukrainian President Volodymyr Zelensky. House Intelligence Chair Adam Schiff, Foreign Affairs Chair Eliot Engel, and Oversight Chair Elijah Cummings designated Pompeo a “fact witness” and called on him to stop intimidating witnesses to “protect himself and the President.”

“Secretary Pompeo was reportedly on the call when the President pressed Ukraine to smear his political opponent,” they wrote. “If true, Secretary Pompeo is now a fact witness in the House impeachment inquiry. He should immediately cease intimidating Department witnesses in order to protect himself and the President.”

The statement warned Pompeo that any effort to intimidate witnesses or prevent them from cooperating with Congress would be “illegal and will constitute evidence of obstruction of the impeachment inquiry.”

“The Committees are operating pursuant to our long-established authorities as well as the impeachment inquiry,” they added.

This is where the official impeachment inquiry pays dividends—not cooperating with the inquiry can be rolled into an obstruction impeachment article.