A major early step of the House Democrats’ impeachment inquiry is to talk to the top administration officials who would have had knowledge about President Trump’s work with Ukraine.

But like a number of other high-profile Trump administration officials, Secretary of State Mike Pompeo is resisting. He said Tuesday in a letter that State Department officials won’t appear this week as the heads of Congress’s investigation requested. It’s possible some of these people might not speak to Congress at all.

And Congress may not have a lot of options left to force potentially key players in its impeachment inquiry to speak to it. The rule book for how to be a check on the executive branch doesn’t include an executive branch unwilling to cooperate.

Pompeo is staking his argument on both procedural and political grounds. Procedurally, he accuses Democrats of not providing a technical document, called a Notice of Deposition, to have his staff testify. He says they were not given enough time, and he is demanding that State Department lawyers be present during testimony to assert executive privilege.

Democrats responded by saying they did everything by the book. “The committees are operating pursuant to our long-established authorities as well as the impeachment inquiry,” read a statement from the chairmen of three key committees who originally requested State Department staff to talk and who have subpoenaed Pompeo for documents. They added: “Secretary Pompeo was reportedly on the call when the president pressed Ukraine to smear his political opponent. If true, Secretary Pompeo is now a fact witness in the House impeachment inquiry.”

The Wall Street Journal reports that Pompeo listened in on the call between Trump and Ukraine’s president that is at the center of the whistleblower allegation that Trump abused his power.

Pompeo’s political reasoning for resisting State Department testimony is perhaps more troubling for Congress’s impeachment inquiry. He is casting Democrats’ request to talk to the people with potential knowledge of the Ukraine allegations as bullying. That fits neatly with Trump’s assessment that the entire impeachment inquiry is designed to target him. It also fits in Trump’s broader plan to blow off Congress at every opportunity. The U.S. attorney general, Trump’s former White House counsel and now the secretary of state are among the top officials who have refused to talk to Congress, even when subpoenaed.

This isn't normal, and that's to Congress's detriment.

As The Washington Post’s Dan Balz wrote recently, the checks and balances are set up to work if both sides respect the governing norms. The founders just didn’t put tools in the Constitution for this. “America’s democratic system, the world’s oldest, is said to be resilient, with institutions strong enough to defend against runaway actors and with checks and balances designed to prevent too much power from building up in any one place or with any one person,” Balz wrote. “Earlier in Trump’s presidency, that appeared to be the case. Right now, however, that is in question.”

We know of one tool Congress still has, and it’s pretty blunt: inherent contempt. Some top Democrats have been talking about using this for weeks. It is a long-dormant power for Congress to fine or jail officials who don’t comply. It hasn’t been used in over a century, but when it has, Congress has detained administration officials for not complying with it. Congress doesn’t have its own jail, so lawmakers could try to use the D.C. jail. As you can see, this idea gets pretty extreme pretty quickly.

The idea of inherent contempt isn’t just on the table for the most liberal Democrats. A group of seven freshman Democrats with military records and/or national security backgrounds wrote an op-ed in The Washington Post last week saying Trump’s actions, if true, are impeachable, and they brought up this idea.

“We call on our colleagues in Congress to consider the use of all congressional authorities available to us, including the power of “inherent contempt” and impeachment hearings, to address these new allegations, find the truth and protect our national security,” they wrote.

As I wrote in September, inherent contempt could overshadow the actual impeachment inquiry. It is arguably more drastic than impeachment because of how rare and dramatic it would be. That’s a problem for Democrats in Congress who are worried that impeachment would give Trump a boost in public sentiment or cost some vulnerable Democrats their seats.

As I also wrote, “the fact that a centuries-old, somewhat crude enforcement tool is even being considered at the highest levels of Congress in 2019 underscores just how much the Trump administration’s disregard for the democratic process has kneecapped Congress’s ability to do anything to oversee the executive branch. They’re out of options except to create their own jail of sorts.”

And it’s safe to say Pompeo knows it.