Pompeo will testify at a Senate Foreign Relations Committee hearing for the first time in 15 months, discussing the State Department's annual budget request.
Foreign Relations Committee Democrats released a report this week that harshly criticized Pompeo's tenure at State, saying he had harmed the department's ability to conduct diplomacy by leaving jobs open for months, treating career diplomats poorly and promoting a culture of retaliation.
"This is not just about an attack on one federal agency; it is a disgrace to American values and leadership, and puts our national security at risk," said Senator Bob Menendez, the foreign relations panel's top Democrat.
Lawmakers are also likely to ask Pompeo about President Donald Trump's abrupt firing in May of Steve Linick, the State Department inspector general, as he investigated arms sales to Saudi Arabia and allegations that Pompeo improperly ordered a taxpayer-funded subordinate to handle personal errands.
Pompeo has denied wrongdoing.
A host of other issues are also on lawmakers' minds, Senate aides said. Among them are deteriorating relations with China, after Washington and Beijing each closed one of the other country's consulates and Pompeo recently announced an end to Hong Kong's special trading status.
Lawmakers also want to ask about tensions with Iran heightened by military exercises in the Gulf and plans to withdraw about 12,000 troops from Germany in fallout from Trump's long-simmering feud with NATO ally Berlin.They also are concerned about Trump's plans to allow more drone exports and reports that Russia offered bounties for the killing of Americans in Afghanistan.