A National Security Council official testified Thursday that Russia has succeeded in exacerbating domestic tensions in the U.S. and delegitimizing the U.S. presidency.

Fiona Hill, a Russia expert, made a direct challenge to Republican members of the House Intelligence Committee, who have seemed to cast doubt on Russian interference in the 2016 election, and to put blame on Ukraine. She asked them to stop promoting falsehoods that promote Russian interests, and warned that Russia is gearing up to interfere in the 2020 campaign.

“President Putin and the Russian security services operate like a super PAC,” she said. “The Russian interest is to delegitimize our entire presidency. The goal of the Russians was to put whoever became president under a cloud… What we’re seeing here, this is exactly what the Russian government was hoping for.”

Hill testified on the fifth day of impeachment hearings. She was joined at the witness table by David Holmes, a foreign service official who serves in Ukraine.

Holmes spoke about meetings in Kiev, including one on July 26 in which he overheard a conversation between President Donald Trump and Gordon Sondland, the ambassador to the European Union. Holmes repeated testimony he had given last week in a closed deposition, saying that he could overhear Sondland tell the president that Ukraine President Volodymyr Zelensky “loves your a–,” and would do anything Trump wanted.

He recalled that Trump asked about “the investigation,” and that Sondland confirmed that Zelensky would do an investigation. The conversation came one day after Trump urged Zelensky to investigate former Vice President Joe Biden and Ukraine’s purported involvement in the 2016 campaign.

After Sondland hung up with the president, Holmes asked if it was true that Trump did not “give a s— about Ukraine.” Sondland confirmed that, and said Trump only cared about “big stuff” that benefits him, such as the Biden investigation, Holmes said.

Sondland neglected to mention this conversation during his deposition. In his testimony before the committee on Wednesday, he said he had remembered the conversation and had no reason to dispute Holmes’ general recollection of it. He did dispute referring directly to Biden, however, saying he understood only that the president and his attorney, Rudy Giuliani, wanted an investigation of Burisma, a Ukrainian gas company. Biden’s son, Hunter Biden, served on the board of the company.

Kurt Volker, a diplomat who also served in Ukraine, testified on Tuesday that he also failed to make the connection between a Burisma investigation and the Bidens, saying the former would be unremarkable while the latter would be obviously improper. He said he only made the connection much later.

Hill and Holmes both testified Thursday that it was clear that Burisma and the Bidens were linked, as Giuliani had been publicly making the connection in stories in the New York Times.

Hill repeated testimony she had given about John Bolton, who was then the national security adviser. She described a meeting in which Bolton sought to make it clear he had nothing to do with a deal whereby Ukraine would launch investigations in exchange for a White House meeting. She said that Bolton instructed her to go tell the lawyers that “I am not part of whatever drug deal that (Chief of Staff Mick) Mulvaney and Sondland are cooking up.”