Former National Security Adviser John Bolton warned U.S. diplomats this summer that Rudy Giuliani could hinder the chances of improving America’s relationship with Ukraine, a State Department official is expected to tell Congress on Wednesday. The Wall Street Journal obtained the written testimony of Christopher Anderson, who served as special adviser for Ukraine negotiations for two years until July 2019. He will testify to House impeachment investigators later today that Bolton supported “increased senior White House engagement” with Ukraine, but was concerned that Giuliani “was a key voice with the president on Ukraine” that could hurt efforts to strengthen the relationship between the governments. Bolton’s alleged warning indicates he was aware of Giuliani’s influence over the president on Ukraine weeks before the controversial July phone call in which the Ukrainians were asked to investigate former Vice President Joe Biden and his son Hunter. Bolton left his post last month.