It was mid-May, days before the inauguration of Ukraine’s newly elected president, and President Donald Trump’s Acting Chief of Staff seemed unusually interested in the guest list. As the White House finalized which U.S. officials would attend the event, National Security Advisor John Bolton kept taking E.U. Ambassador Gordon Sondland off its list, and Mick Mulvaney’s office kept adding him back on.

Mulvaney’s insistence on Sondland’s attendance at the inauguration surprised Fiona Hill, the National Security Council’s director for Russia and Europe, whose office was across an alley from Mulvaney’s on the White House grounds. Ukraine is not part of the European Union and Sondland, the U.S. ambassador to the European Union, had no official role at that point in the country.

But, as Hill told House investigators in closed-door testimony on Oct. 14, the wealthy Trump donor and hotel magnate had an unusual backchannel directly to Mulvaney and had been repeatedly inserting himself into U.S. Ukrainian affairs. A month after the inauguration—which Sondland did attend—the ambassador told Hill that President Trump had put him in charge of Ukraine policy, which was news to her as Ukraine was in her portfolio to oversee at the White House. Hill said she repeatedly saw Sondland coming to the White House to meet with Mulvaney without informing her, as protocol would normally dictate.

The House impeachment investigation has thrust Mulvaney into the spotlight, as Democrats try to bolster their case that President Trump dangled a White House meeting and military aid to pressure Ukraine to open politically expedient investigations. Transcripts released earlier this month put Mulvaney at the center of efforts to pressure Ukraine to launch those probes. Just how extensive and sustained his involvement was during the key months surrounding the impeachment inquiry will come into sharper focus as Sondland takes the stand on Wednesday and investigators try to zero in on Trump’s direct role.

Mulvaney, a three-term Congressman from South Carolina known for wearing brightly patterned suits and ties, made his name on the Hill as a deficit hawk and critic of federal spending. In February 2017, Trump tapped him to be his Director of the Office of Management and Budget (OMB), giving Mulvaney insight into nearly every dollar the U.S. government spends, including foreign aid. In addition to his current duties as acting White House Chief of Staff, Mulvaney has maintained the title as head of OMB, putting him in a unique position to know about the discussions around Ukrainian aid.

Just how central a role Mulvaney was playing in U.S.-Ukrainian affairs during the months at the heart of the impeachment inquiry was highlighted during a July 10 meeting in one of the most secure corners of the West Wing, according to testimony from Hill and Lt. Col. Alexander Vindman. Sondland and other officials were pressed around a long table in the windowless, wood-paneled Ward Room a few feet from the Situation Room, talking to Ukrainian officials about whether Trump would follow through on his offer to host Ukraine’s president at the White House.

Sondland had a message from Mulvaney, according to the description of the meeting given to House investigators by Vindman, the White House’s Ukraine expert at the time. The visit required a “deliverable” from Ukraine: investigations into the 2016 elections and the Ukrainian energy company Burisma. “He just said that he had had a conversation with Mr. Mulvaney, and this is what was required in order to get a meeting,” Vindman said.

Earlier that same day, Bolton had cut short a meeting with the Ukrainian officials after Sondland said an Oval Office meeting between the two presidents was contingent on Ukraine launching investigations. Bolton directed Hill to tell the top National Security Council lawyer about Sondland’s statement, telling her: “I’m not part of whatever drug deal Sondland and Mulvaney are cooking up on this.”

By mid-July, Mulvaney further ratcheted up the pressure on Ukraine by ordering the Office of Management and Budget to put U.S. military aid on hold. “We were told that it actually came as a direction from the Chief of Staff’s office,” Hill told investigators about the freeze. The military aid to Ukraine was ultimately released on Sept. 11, two months later.

When Mulvaney spoke to White House reporters on Oct. 17, he acknowledged that he “was involved with the process by which the money was held up temporarily.” He said it was done for three reasons: concern over corruption in Ukraine, concern that European countries were not contributing enough aid, and the White House’s desire that Ukraine cooperate with the U.S. Department of Justice into an ongoing investigation into the 2016 election.

“That’s completely legitimate,” Mulvaney said, adding: “We do that all the time with foreign policy.” Mulvaney later walked back his remarks by saying in a statement there was “absolutely no quid pro quo between Ukrainian military aid and any investigation into the 2016 election.”

So far Mulvaney has refused to testify, but Sondland will appear for a public hearing on Wednesday and is expected to be grilled about his conversations with Mulvaney and Trump. Hill will also likely be asked about Mulvaney’s role in freezing Ukraine aid when she appears before Congress on Friday. Mark Sandy, a senior career official at the Office of Management and Budget, testified to House investigators behind closed doors on Saturday, and a transcript of his testimony is expected to be released in the coming days. Other senior officials have refused to testify including Russell T. Vought, the No. 2 official at OMB, and Michael Duffey, who helped execute Trump’s order to hold the funding.

As House Democrats push forward with impeachment hearings, fresh public testimony is expected to uncover new details about Mulvaney’s spot at the center of the effort. As chief of staff, Mulvaney has developed a reputation allowing more open access to Trump and trying to execute Trump’s demands, rather than side step them, or dial them back, like his predecessor John Kelly. The outcome of the impeachment inquiry will also deliver a verdict on whether that was in Trump’s best interest.

— With reporting by Vera Bergengruen/Washington

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