WASHINGTON – President Donald Trump called her "bad news." And Trump's personal lawyer, Rudy Giuliani, sought her removal as ambassador to Ukraine, suggesting she was undermining the president.

Marie Yovanovitch – a career diplomat with decades of overseas experience – pushed back, telling lawmakers in a closed-door meeting that she had been ousted from her job over "unfounded and false claims." She also warned that the State Department was being "hollowed out from within," posing risks for the country's national security interests.

Yovanovitch, 60, spent hours on Capitol Hill giving a deposition for House Democrats' impeachment inquiry into whether Trump abused his office by soliciting foreign interference in the 2020 election. At the center of the probe is a July 25 phone call in which Trump urged Ukraine's president to investigate his political rival, former Vice President Joe Biden, and Biden's son Hunter. Giuliani, who has met with Ukrainian officials, has acknowledged pushing Ukraine to investigate Biden.

Federal prosecutors have revealed a plot by two Ukrainian-born business partners to enlist the help of a GOP congressman for the purpose of pressuring the Trump administration to remove Yovanovitch from her post as ambassador to Ukraine.

The two, Lev Parnas and Igor Fruman, pledged to raise $20,000 for the lawmaker, according to court documents. The congressman wrote last year to Secretary of State Mike Pompeo urging Yovanovitch's ouster. She was recalled in May.

Deep dive:Trump's conspiracy theories thrive in Ukraine, where a young democracy battles corruption and distrust

Parnas and Fruman are business associates of Giuliani and arranged a meeting for him with a Ukrainian prosecutor. The pair were charged in connection with alleged schemes to funnel foreign money to U.S. political campaigns, federal authorities said.

Marathon Capitol Hill session

Yovanovitch answered questions during a day-long, closed-door session before three House committees – Foreign Affairs, Intelligence, and Oversight and Reform – that are leading the impeachment inquiry.

The deposition by Yovanovitch, a State Department employee temporarily serving as a fellow at Georgetown University in Washington, defied the White House and her immediate boss, Pompeo.

The State Department, at the direction of the White House, instructed the ambassador not to appear for her interview Friday, according to a statement from House Democrats. In response, the House Intelligence Committee issued a subpoena early Friday to compel her testimony, Democratic lawmakers said in a statement.

Pushing back:Pompeo defends Ukraine phone call, blasts Dems 'who are trying to take down this president'

Pompeo has defended the president's conduct with Ukraine.

"We ask our friends and allies and partners and indeed our adversaries to do things for us all the time," Pompeo told The Tennessean while visiting Nashville to speak at a conference of the American Association of Christian Counselors. "It’s completely common to do so."

But in her opening statement to the lawmakers, Yovanovich gave a forceful defense of American diplomacy that seemed to strike broadly at how the State Department has been treated in the Trump era and specifically at what Giuliani was doing in Ukraine.

'Pressured':Ex-Ukraine envoy Marie Yovanovitch says Trump 'pressured' State Dept. to remove her

"We need to rebuild diplomacy as the first resort to advance America’s interests and the front line of America’s defense," her statement read. "I fear that not doing so will harm our nation’s interest, perhaps irreparably."

"That harm will come not just through the inevitable and continuing resignation and loss of many of this nation’s most loyal and talented public servants," she said. "It also will come when those diplomats who soldier on and do their best to represent our nation face partners abroad who question whether the ambassador truly speaks for the President and can be counted upon as a reliable partner. The harm will come when private interests circumvent professional diplomats for their own gain, not the public good."

A Giuliani target: 'Singled out for retribution'?

Yovanovitch became America’s top diplomat in Ukraine shortly before Trump’s 2016 election. She brought three decades of experience in the foreign service, including stints as the U.S. ambassador to Armenia and to the Kyrgyz Republic.

In Kiev, Yovanovitch pushed Ukrainian officials to crack down on the country’s endemic corruption, fueled by a circle of politically connected oligarchs. She specifically criticized Yuriy Lutsenko, then Ukraine’s chief prosecutor, for not aggressively pursuing corruption cases.

Lutsenko had been widely seen inside Ukraine as weak on corruption, according to a complaint from an intelligence community whistleblower. The complaint, which sparked the impeachment inquiry, alleged that Trump used the power of his office to solicit foreign interference in the 2020 election, by pressing Ukrainian President Volodymyr Zelensky to investigate Biden and his son, Hunter, who sat on the board of a Ukrainian gas company. Ukrainian officials say they have no evidence of wrongdoing by the Bidens.

In his call with Zelensky, Trump criticized Yovanovitch and told the Ukrainian president she's “going to go through some things," though he did not elaborate.

Trump had already pulled Yovanovitch from her Ukraine ambassador post in May – before her tenure there was supposed to end.

In May, Giuliani told a Ukrainian journalist that Yovanovitch was "removed ... because she was part of the efforts against the president."

Giuliani further targeted Yovanovitch in a packet of "disinformation" that he gave to State Department officials earlier this year. The dossier was full of debunked allegations and political smears targeting the president’s perceived enemies, and it eventually made its way to lawmakers leading the impeachment probe.

After a briefing on the Giuliani dossier by the State Department's chief watchdog, the three chairmen leading the impeachment inquiry said it raised "troubling" new questions about efforts inside and outside the Trump administration to target Yovanovitch and others.

More than 50 current and former ambassadors have come to Yovanovitch's defense, signing a letter asking Trump to ensure that Yovanovitch isn’t “singled out for retribution for partisan, political reasons.” Trump’s reference to Yovanovitch as “going to go through some things” during his call with Zelensky worried the ambassadors.

'A cool customer'

The grilling of Yovanovitch on Capitol Hill was led by staff attorneys on the impeachment panel.

In her opening statement to the committee, Yovanovitch said she had "only minimal contacts" with Giuliiani. And she said she didn't know why the former mayor attacked her integrity.

"But individuals who have been named in the press as contacts of Mr. Giuliani may well have believed that their personal financial ambitions were stymied by our anti-corruption policy in Ukraine," she said.

Harold Hongju Koh, a professor of international law at Yale University who worked with Yovanovitch at the State Department, described her as a "straight shooter, by the book."

"She’s a cool customer" who is deeply respected for her foreign service credentials and her eastern Europe expertise, he said.

Other State Department officials who have been called for depositions include:

• Kurt Volker, a onetime U.S. special representative for Ukraine and who played a role arranging meetings between Giuliani and Zelensky’s representatives. He resigned after his name was mentioned in the whistleblower complaint and Giuliani posted private text messages, showing Volker introduced him to a top adviser to the Ukrainian president. Volker's testimony hasn't been released, but in his opening statement, he said Trump sought to fight corruption in Ukraine. "He said that Ukraine was a corrupt country, full of 'terrible people,'" Volker recalled. "He said they 'tried to take me down'.”

•George Kent, the deputy assistant secretary in the European and Eurasian Bureau at State Department, which oversees policy toward Ukraine.

• T. Ulrich Brechbuhl, a counselor at the State Department who provides strategic guidance to Pompeo. The whistleblower complaint said he was on the call as Trump spoke to Zelensky.

Contributing: Ledyard King

More about the House impeachment investigation against President Trump:

Whistleblower says Trump used 'the power of his office' to solicit foreign help to discredit Joe Biden

Democrats subpoena Trump's personal attorney, Rudy Giuliani, for Ukraine documents

Democrats accuse Pompeo of 'stonewalling,' after he pushes back on impeachment requests