Pompeo says State Dept. officials won't show up for scheduled impeachment depositions this week

[SomewhereInTheMiddle]

35. He too can be impeached

“The President, Vice President and all Civil Officers of the United States, shall be removed from Office on Impeachment for, and Conviction of, Treason, Bribery, or other high Crimes and Misdemeanors.”
— U.S. Constitution, Article II, section 4

The House can choose to expand the impeachment investigation to include officials who refuse to cooperate. That is one of the checks the Legislative branch has on the Executive. Although it is likely that the Senate would fail to convict in the SecState's case as well as the POTUS'.

Another is the power of the purse. The House can choose to defund some or all of the State Department or Justice Department or .... This would be massively controversial and highly irresponsible. But choosing to defund parts of the departments' budgets might be done as a targeted statement to make a stand - say the Secretary's staff or travel budget.

The third option I see is the Contempt of Congress route. I'd imagine the President can pardon anyone cited for Contempt in a federal venue, but I could be wrong. He cannot pardon from impeachment and conviction or from budget cuts.

Letting Executive officials ignore COngress breaks the delicate balance of power between the branches. It is bad for the nation.