They want Pompeo and others to refuse to comply, so they can charge obstruction.
Via Daily Wire:
Three House committees last week sent subpoenas to Secretary of State Mike Pompeo regarding his involvement with President Donald Trump’s phone call with the Ukrainian president back in July.
The House Foreign Affairs, Intelligence, and Oversight committees all sent subpoenas to Pompeo demanding “documents related to efforts by President Donald Trump and his personal lawyer, Rudy Giuliani, to dig up dirt on 2020 presidential candidate Joe Biden,” reported The Daily Beast.