They're setting their sights on President Donald Trump's former national security adviser following leaked revelations from his forthcoming book about how Trump directly tied nearly $400 million in military aid to Ukraine to political favors from Kyiv. Bolton, who submitted the manuscript of The Room Where It Happened to the White House for review on Dec. 30, has said he'll testify if he's subpoenaed.
Why does it matter? The timing is particularly key, since the Senate's expected to vote this week on whether to allow witnesses in the impeachment trial.
Don't miss OZY's profile of the Democrats' hired impeachment gun.