Andrii Derkach, the Ukrainian parliamentarian who is one of Giuliani’s principal contacts, was mentioned in an August intelligence assessment that described a concerted Russian effort to disparage Biden. A Treasury Department sanction announcement from last month characterized Derkach as an “active Russian agent for over a decade.”

Derkach in recent months has leaked recordings of calls Biden had as vice president with Ukraine’s then-leader, audio the Biden campaign contends is heavily edited. Despite his own administration’s warnings on Derkach, Trump has promoted those recordings on Twitter.

Giuliani has not been shy about discussing his foreign contacts, including with Derkach. In December, Derkach posted on his Facebook page photos of him and Giuliani meeting in Kyiv.

Frustration about Giuliani in the West Wing has long run rampant, with those around the president warily watching Giuliani’s efforts to bring down the Bidens and fearful they could boomerang back on the president.