Johnson demands Zelensky fire his ambassador to the U.S.

• The Republican-led House Oversight Committee is investigating the trip, in which Zelensky was flown in a U.S. Air Force jet — a routine procedure for foreign officials traveling within the U.S.

Driving the news: In a letter to Zelensky, Johnson wrote that the trip was "in a politically contested battleground state, was led by a top political surrogate for Kamala Harris, and failed to include a single Republican because — on purpose — no Republicans were invited."

• Zelensky met with Pennsylvania Gov. Josh Shapiro and U.S. Sen. Bob Casey, both Democrats.
• Johnson alleged that the tour was "clearly a partisan campaign event designed to help Democrats" and that it has "caused Republicans to lose trust in Ambassador Markarova's ability to fairly and effectively serve as a diplomat in this country."
• The Ukrainian Embassy did not immediately respond to a request for comment.

Zoom out: The demand comes amid an escalating war of words between Zelensky and allies of former President Trump.

• Zelensky criticized Trump and his running mate, Sen. JD Vance (R-Ohio), in an interview with the New Yorker, calling Vance "too radical" on Ukraine aid and saying Trump doesn't know how to end the war with Russia.
• Trump shot back by questioning U.S. aid to Ukraine and suggesting Zelensky wants to see Vice President Harris win the election.
• In addition to the Oversight probe, a group of House Republicans has urged the Justice Department and Pentagon inspectors general to investigate the trip.