WASHINGTON — John R. Bolton, President Trump’s former national security adviser, knows about “many relevant meetings and conversations” connected to a pressure campaign on Ukraine that House impeachment investigators have not yet been informed of, his lawyer told lawmakers on Friday.
The lawyer, Charles J. Cooper, tucked the tantalizing assertion into a letter to the chief House lawyer in response to committee chairmen who have sought Mr. Bolton’s testimony in their impeachment inquiry but expressed unwillingness to go to court to get an order compelling it.
Mr. Cooper did not elaborate on what meetings or conversations he was referring to, leaving it to House Democrats to guess at what he might know.
But the hints about what Mr. Bolton might be able to add came as new details emerged from the impeachment inquiry about how an effort by Mr. Trump’s allies to use the United States’ relationship with Ukraine to accomplish the president’s political goals opened a bitter rift inside the White House.
According to testimony made public on Friday, the push, spearheaded in large part by Rudolph W. Giuliani, the president’s personal lawyer, pitted Mr. Bolton, who sought repeatedly to resist it, against Mick Mulvaney, the acting chief of staff who senior officials said may have played a central role in carrying it out.
Mr. Mulvaney himself failed to appear on Friday for a scheduled deposition in the inquiry, a day after Mr. Bolton. Their absences underscored dilemmas impeachment investigators face as they wrap up weeks of private fact-finding and look toward public hearings beginning next week. They are closing in on an ever more elaborate account by administration witnesses of how the pressure campaign on Ukraine unfolded, but have been unable to obtain the firsthand testimony of those closest to the president.
Transcripts of testimony by Fiona Hill, the former senior director for Russia and Europe at the National Security Council, and Lt. Col. Alexander S. Vindman, the Ukraine expert there, described how the council under Mr. Bolton became consumed with trying to thwart Mr. Giuliani’s efforts to bend Ukraine policy to the president’s political advantage.
They said there was evidence Mr. Mulvaney was involved in setting up a quid pro quo in which Ukraine could not receive a White House meeting unless top officials there committed to investigations that Mr. Trump wanted. And they showed how the foreign policy officials most deeply knowledgeable about Ukraine were sidelined and forced to act as mere spectators — in some instances watching for Mr. Giuliani’s freewheeling appearances on cable news for clues — in dealing with the relationship with Kiev.
Ms. Hill said Mr. Bolton repeatedly sought to cut off the influence of Mr. Giuliani, whom he referred to as a “hand grenade.”
Mr. Bolton was “closely monitoring what Mr. Giuliani was doing and the messaging that he was sending out,” she told investigators, adding that he warned “repeatedly that nobody should be meeting with Giuliani.”
At the same time, Ms. Hill and Colonel Vindman said, Mr. Mulvaney appeared to be pushing to use a coveted White House meeting for Ukraine’s leader as leverage to secure investigations into former Vice President Joseph R. Biden Jr. and his son Hunter Biden, as well as possible Democratic collusion with Ukraine in 2016.
Ms. Hill testified that Gordon D. Sondland, the United States ambassador to the European Union, told the Ukrainian officials in July during a meeting at the White House “about how he had an agreement with Chief of Staff Mulvaney for a meeting with the Ukrainians if they were going to go forward with investigations.” Colonel Vindman told investigators he heard Mr. Sondland say his offer had been “coordinated” with Mr. Mulvaney.
Afterward, Mr. Bolton ordered Ms. Hill to tell White House lawyers he was not part of “whatever drug deal Sondland and Mulvaney are cooking up on this.”
Unlike most of those who have testified so far, though, Mr. Bolton would bring knowledge of what the president himself said about the matter. Most of the witnesses have described what people around the president said, but few recounted any direct conversations with Mr. Trump. As his national security adviser who saw him daily, Mr. Bolton presumably could take investigators into the Oval Office as none of their witnesses have.
House Democrats complained that Mr. Bolton was stiff-arming them, but said they would not subpoena him because they did not want to get dragged into lengthy court proceedings. Instead, Democrats have suggested that they may cite the refusal to testify as evidence of obstruction of Congress by the president, which could form its own article of impeachment.
In his letter, Mr. Bolton’s lawyer argued that his client would be willing to talk to investigators, but only if a court rules that he should ignore White House objections.
Mr. Bolton’s former deputy, Charles M. Kupperman, represented by the same lawyer, filed a lawsuit seeking guidance from the federal courts on competing demands by the executive branch, which has ordered them not to testify, and the legislative branch, which has issued subpoenas directing them to. But Democrats have said they will not pursue time-consuming litigation on the matter, arguing that it is a stalling tactic.
Mr. Mulvaney defied a House subpoena on Friday morning, citing instructions that he was absolutely immune from testifying.
Investigators were already eager to question Mr. Mulvaney after his admission in the White House briefing room last month of a quid pro quo linking the military aid for Ukraine to that country’s announcement of investigations that Mr. Trump wanted. Hours later, Mr. Mulvaney said he was misunderstood and retracted the statement.
At the White House, Mr. Trump derided the coming public hearings as a “hoax,” even as he sought to project confidence that he would not be brought down by a recent stream of damning testimony from officials in his own administration who have cooperated with the impeachment inquiry.
“They shouldn’t be having public hearings,” Mr. Trump told reporters as he left the White House to travel to Georgia. Reversing himself, the president also sought to put distance between himself and Mr. Sondland, a key witness at the center of the inquiry who was a campaign donor to the president and was rewarded with his plum diplomatic post. “I hardly know the gentleman,” Mr. Trump said.
House Republicans took a significant step to ready a defense of Mr. Trump on Capitol Hill. Representative Kevin McCarthy of California, the top House Republican, confirmed Friday what lawmakers had been speculating about for days: He is shuffling the makeup of a key committee to allow one of Mr. Trump’s most outspoken allies to take part in public hearings.
Mr. McCarthy said Friday afternoon that Representative Jim Jordan of Ohio would temporarily move onto the Intelligence Committee, swapping with another Republican lawmaker.
“Jim Jordan has been on the front lines in the fight for fairness and truth,” Mr. McCarthy said in a statement. “His addition will ensure more accountability and transparency in this sham process.”
The testimony laid out in the transcripts released on Friday showed for the first time the extent of the turmoil in the National Security Council — the usually staid White House body responsible for coordinating foreign policy throughout the government — first because of Mr. Giuliani’s work and the conspiracies he appeared to be peddling, and later by Mr. Trump’s apparent embrace of his lawyer’s agenda.
Ms. Hill described going home at night and watching cable television to track Mr. Giuliani’s public statements about Ukraine, and said Mr. Bolton would turn up the volume if Mr. Giuliani appeared on the TV in his office.
“And then I would have to go onto YouTube or whatever else I could find, you know, kind of replays of things because people were constantly saying to me: ‘My God, have you seen what Giuliani is saying now?’” she testified.
After learning in mid-July that military aid to Ukraine had been abruptly frozen, Colonel Vindman told investigators that members of the National Security Council sent a series of memos to Mr. Bolton seeking to understand what they considered an “abnormal” process that led to the flow of aid being stopped.
Days later, Colonel Vindman drafted a “presidential decision memorandum” for Mr. Bolton to present to Mr. Trump. The memo discussed the importance of the aid for Ukraine and recommended that Mr. Trump release the hold, but it was never signed. Colonel Vindman said he and others were trying to “navigate this minefield” on Ukraine.
Both Colonel Vindman and Ms. Hill described being deeply alarmed by a July phone call between Mr. Trump and President Volodymyr Zelensky of Ukraine. During the call, which is now at the center of the impeachment inquiry, Mr. Trump told Mr. Zelensky that he would like him to do a “favor” by investigating the Bidens and the allegations related to 2016.
“There was no doubt,” Colonel Vindman said, as he listened to the call that Mr. Trump was asking for a “deliverable” from Mr. Zelensky in exchange for a White House meeting.
Ms. Hill, who had already left the White House when the call was placed, said it only confirmed to her that Mr. Giuliani’s efforts had successfully influenced the president.
“My worst nightmare is the politicization of the relationship between the U.S. and Ukraine and, also, the usurpation of authorities, you know, for other people’s personal vested interests,” Ms. Hill said. “And there seems to be a large range of people who were looking for these opportunities here.”
Top White House national security advisers were also dismayed that Mr. Trump specifically invoked an unproven theory that Ukraine, rather than Russia, interfered in the 2016 presidential election, possibly in coordination with Democrats. Mr. Giuliani and allies in Ukraine had tried to advance the theory in public and with Mr. Trump, but the president’s advisers had spent years trying to combat it.
Ms. Hill said Thomas P. Bossert, Mr. Trump’s former homeland security adviser, and Mr. Bolton’s predecessor, H.R. McMaster, “spent a lot of time” in the first year of Mr. Trump’s presidency refuting the claim.
“It is a fiction that the Ukrainian government was launching an effort to upend our election,” Ms. Hill said during one heated exchange with Republicans during her deposition. “If you’re also trying to peddle an alternative variation of whether the Ukrainians subverted our election, I don’t want to be part of that, and I will not be part of it.”