WASHINGTON (AP) — Former U.S. Ambassador to Ukraine Marie Yovanovitch told lawmakers Friday that President Donald Trump pressured the State Department to oust her from her position.

Yovanovitch said in an opening statement obtained by The Associated Press that she was “abruptly” recalled in May and told the president had lost confidence in her. She said she was told by an official that there was a “concerted campaign against me” and that Trump had pressured officials to remove her for almost a year.

“Although I understand that I served at the pleasure of the president, I was nevertheless incredulous that the U.S. government chose to remove an ambassador based, as best as I can tell, on unfounded and false claims by people with clearly questionable motives,” Yovanovitch wrote in the statement.

Yovanovitch appeared on Capitol Hill Friday for a deposition in the Democrats’ impeachment inquiry, accepting lawmakers’ invitation to testify despite Trump’s declaration that no one in his administration wouldn’t cooperate with the probe. The Democrats are investigating Trump’s dealings with the Ukrainian president.

Yovanovitch is now a State Department fellow at Georgetown University. Trump said earlier this week that he would block all officials from testifying, saying the probe was unfair and “illegitimate.” It was unclear if Yovanovitch’s appearance signaled a shift in that strategy or if she was breaking with White House orders.

Democrats are investigating Trump’s pleas to Ukrainian officials to launch investigations of political rival Joe Biden and his family and to probe Ukraine’s involvement in the 2016 presidential election. Yovanovitch was recalled from Kyiv as Rudy Giuliani — who is Trump’s personal attorney and has no official role in the U.S. government — pushed Ukrainian officials to investigate baseless corruption allegations against the Bidens.

Yovanovitch was removed from her post after insisting that Giuliani’s requests to Ukrainian officials for investigations be relayed through official channels, according to a former diplomat who has spoken with her.

In a July 25 phone call, Trump told Ukrainian President Volodymyr Zelenskiy that Yovanovitch was “bad news,” according to a partial transcript released by the White House. Neither Giuliani nor Trump has publicly specified their objections to Yovanovitch.

Businessmen with ties to Giuliani lobbied a U.S. congressman in 2018 for help ousting Yovanovitch, according to an indictment made public Thursday following the men’s arrest. It alleges that the men leveraged a flurry of GOP political donations to force Yovanovitch’s removal, an effort prosecutors say was aided by laundered foreign money.

The former diplomat who spoke with Yovanovitch said the ambassador refused to do “all this offline, personal, informal stuff” and made clear that the U.S. government had formal ways to request foreign governments’ help with investigations. The former diplomat insisted on anonymity to disclose the private conversation.

The State Department traditionally relies on mutual legal assistance treaties, under which U.S. and foreign officials agree to exchange evidence and information in criminal investigations.

Yovanovitch was speaking to the House Intelligence, Foreign Affairs and Oversight and Reform committees behind closed doors Friday. The committees are scheduled to talk to several other U.S. diplomats next week, as well.

READ MORE: Who’s who in the Trump impeachment inquiry?

On Monday, Fiona Hill, a former White House adviser who focused on Russia, is expected to testify. Three current State Department officials also are tentatively scheduled next week — Deputy Assistant Secretary of State George Kent, U.S. Ambassador to the European Union Gordon Sondland, and Ulrich Brechbuhl, a State Department counselor.

Sondland was originally scheduled for a deposition this past Tuesday but did not show up. Trump tweeted immediately afterward that he couldn’t let Sondland testify because the Democratic-led probe was “compromised.”

The committees subpoenaed Sondland hours later for a deposition next week, and his attorneys said Friday he would testify on Oct. 17, despite the administration’s position.

“Notwithstanding the State Department’s current direction to not testify, Ambassador Sondland will honor the Committees’ subpoena, and he looks forward to testifying on Thursday,” said a statement from attorneys Robert Luskin and Kwame Manley. “Ambassador Sondland has at all times acted with integrity and in the interests of the United States. He has no agenda apart from answering the Committees’ questions fully and truthfully.”

The statement said, however, that Sondland would not be able to product documents “concerning his official responsibilities,” as they were controlled by the State Department.

Democrats want to ask him about text messages released last week that show him and two other U.S. diplomats acting as intermediaries as Trump urged Ukraine to investigate Ukraine’s involvement in the 2016 U.S. election and Hunter Biden’s involvement with a gas company there.

Earlier this week, the White House sent Congress a letter outlining its opposition to the impeachment probe and refusing to cooperate with requests for information, including interviews with administration officials. The House committees have moved to subpoena officials instead.

READ MORE: Support for Trump impeachment inquiry rises, new poll shows

On Thursday, 10 Democratic senators sent a letter to Secretary of State Mike Pompeo demanding an explanation for Yovanovitch’s removal before the end of her three-year assignment.

“In particular, her early recall raises questions about whether you put the personal interests of the President above the Department’s career personnel or U.S. foreign policy,” they wrote.

Even before the testimony, the attention on Yovanovitch was renewed Thursday after U.S. prosecutors arrested two Florida businessmen tied to Giuliani, charging them with campaign finance violations. An indictment filed in the case alleged that the men, who were raising campaign funds for a U.S. congressman, asked him for help in removing Yovanovitch, at least partly at the request of Ukrainian government officials.

Yovanovitch has led U.S. embassies in Kyrgyzstan and Armenia and is now a State Department fellow at Georgetown University. The director of the Georgetown program, Barbara Bodine, said the former envoy is declining all requests for interviews.

Former colleagues of Yovanovitch said Trump allies’ characterizations of her as politically motivated are off-base.

She is “a top-notch diplomat, careful, meticulous, whip smart,” and unlikely to have badmouthed Trump, either to Ukrainian officials or her colleagues, said John Herbst, a predecessor as ambassador in Ukraine who worked alongside Yovanovitch there in the early 2000s.

Yovanovitch has always known that the role of diplomat “wasn’t about her” but about “serving American national interests and supporting the people around her,” said Nancy McEldowney, a former U.S. ambassador to Bulgaria who now directs a Foreign Service program at Georgetown.

Associated Press Writers Matthew Lee and Jocelyn Noveck contributed to this report.