Four Democratic House committee chairs on Friday asked the Justice Department's inspector general to launch an "emergency investigation" into whether Attorney General Bill Barr and U.S. Attorney John Durham, his appointee, are taking actions that could "improperly influence the upcoming presidential election."

Catch up quick: Last year, Barr tapped Durham to conduct a sweeping investigation into the origins of the FBI's 2016 Russia probe, after he and President Trump claimed that it was unjustified and a "hoax."

• Although Justice Department Inspector General Michael Horowitz found "serious performance failures" by some FBI officials, he ultimately concluded that the FBI's investigation was not tainted by political bias.
• Nora Dannehy, a senior prosecutor who worked with Durham on his investigation, abruptly resigned from the DOJ last week.
• The DOJ did not immediately respond to a request for comment.

What they're saying: The committee chairs are concerned that Barr could make "public disclosures" or "issue reports" before the election about the Durham investigation in ways that "appear intended to benefit President Trump politically."

• "Few actions would prove more damaging to public confidence in the integrity of the DOJ and our democratic process than the perception that federal prosecutorial power can be used to prejudice a pending investigation or influence an upcoming election," the committee chairs wrote to Horowitz.

The big picture: Congressional Democrats have ramped up accusations that Barr is working to benefit Trump's re-election, and in May went so far as to allege that he is doing the president's "political bidding" by interfering in ongoing criminal cases — including dropping the agency's prosecution of former national security adviser Michael Flynn.

Read the letter.