Looks like they’re going for Obstruction of Congress as their best defense:

Secretary of State Mike Pompeo on Tuesday sternly objected to a move by the U.S. House of Representatives to obtain depositions from five current and former State Department officials as part of an impeachment inquiry targeting President Donald Trump, accusing Democrats of bullying and intimidation.

Not a good look with reports being that Pompeo was actually on the shakedown call with Ukraine.