Secretary of State Mike Pompeo as of Thursday had yet to say a public word about the U.S. ambassador to Ukraine who fought against corruption there and has been repeatedly besmirched by President Donald Trump and his personal lawyer, Rudy Giuliani.

Marie Yovanovitch, who was recalled early from her post this spring, is scheduled for a deposition Friday with three committees in the House of Representatives, but it is unclear whether she will be allowed to show up after the U.S. ambassador to the European Union was blocked by the Trump administration from testifying on Tuesday.

Either way, the manner in which Yovanovitch has been treated by Trump and the silence from Pompeo has already rankled many rank and file at the State Department, according to half a dozen current and former officials, who are also upset by the administration's use of career diplomats in the president's efforts to pressure Ukraine to investigate his political opponents.

At his arrival as secretary, Pompeo was seen as a much-needed improvement over his predecessor, Rex Tillerson. But many career diplomats tell ABC News they are increasingly fed up with the former congressman and CIA director, in particular over an effort to penalize more than 100 State Department employees for having emailed Hillary Clinton's private email address during her time as secretary, and because of how he's painted himself as the department's defender in a battle with House Democrats over documents and witness testimony, while keeping quiet on Yovanovitch.

The State Department did not respond to several requests for comment this week. But Pompeo has repeatedly defended the president and Giuliani's effort to push Ukraine to investigate former Vice President Joe Biden and his son Hunter, as well as the effort to investigate leaks during the 2016 campaign about Trump's campaign manager Paul Manafort, who has since gone to prison for his corrupt business dealings in Ukraine, among other charges.

Yovanovitch is still an active member of the U.S. diplomatic corps, known as the Foreign Service. She is teaching this school year at Georgetown University after being recalled in May two months early from her post as ambassador to Ukraine despite being nearly unanimously praised as a "professional of impeccable integrity, someone with a stellar career that has never had the slightest suggestion of impropriety," as retired ambassador Nancy McEldowney described her.

Giuliani, who said at the time she was "fired," had been spreading misinformation about Yovanovitch for months before that. Yovanovitch had been trying to tackle corruption, including giving a major speech in March that criticized the lack of investigative progress and in particular blamed Ukraine's then-prosecutor general Yuriy Lutsenko. In response, Lutsenko accused Yovanovitch of giving him a "do-not-prosecute" list and blocking him and other officials from traveling to the U.S. to present evidence against the Bidens.

At the time, the State Department said the allegation was an "outright fabrication" and "does not correspond to reality." But Giuliani and some pro-Trump media personalities promoted Lutsenko's charges. Within months, she was gone from Kyiv -- a decision that Pompeo reportedly supported.

"It does not escape notice that he was on the call where Trump sold the U.S. Ambassador to Ukraine up the river,” said another Foreign Service officer, who added that he did not believe the secretary was acting in the best interests of rank and file employees, but who, like others interviewed by ABC News, would speak only on condition that their name not be used for fear of retribution.

During his controversial call with Ukraine's President Volodymyr Zelenskiy in July, which Pompeo listened in on, Trump bashed Yovanovitch as "bad news." More recently, he told reporters on Oct. 3, "I heard very, very bad things about her for a long period of time. Not good."

"Pompeo's participation in her firing [from her post in Ukraine] was so dispiriting not just because of Yovanovitch's stellar career, but also the impact on all career officials -- that someone doing their job with integrity and confidence could run afoul of a partisan scheme and be removed because of it," said McEldowney, who led the Foreign Service Institute, the diplomatic corps' training facility, under Trump and Barack Obama and was named ambassador to Bulgaria by George W. Bush. "It goes against the apolitical and nonpartisan framework that the Foreign Service and our diplomacy is founded upon."

Yovanovitch has been scheduled to appear before the House Oversight, Intelligence, and Foreign Affairs committees on Friday, according to committee staff. Democrats still expect that she will show up, but two sources told ABC News that although she wants to, there are efforts to stop her after the administration blocked U.S. ambassador to the European Union Gordon Sondland from appearing on Tuesday.

As a current State Department employee, Yovanovitch would not go against a department decision that she could not attend, according to one source.

The controversy over Ukraine is not the only source of tension.

At least 125 former and current State Department employees have been targeted for having emailed former Secretary Clinton's private account, which has been retroactively marked classified, according to two sources. That means the department has now flagged their files with a letter that says they mishandled classified information. While no one has faced charges in connection with this investigation, this kind of letter could imperil future job prospects.

A senior State Department official denied to the Washington Post, which first reported the story, that officials were being targeted, saying it was a standard investigation that has taken time: "This has nothing to do with who is in the White House."

But the investigation has been perceived as retaliation for career officials who were assigned to jobs working closely with Clinton or a way to block former officials from serving in the State Department again.

"We're angry over the way our folks have been treated," said another senior diplomat who added they are also "worried most about mid-career people leaving" and the lack of mid-career promotions: "We're losing a whole generation of diplomats."

Pompeo has worked with the White House and Senate to fill many top positions at the State Department and embassies around the world. He has four of the six Under Secretary roles filled by Senate-confirmed nominees, more than his predecessor, with 33 vacancies out of 188 ambassadorships -- dozens fewer than under Tillerson.

But the number of ambassadors that are career diplomats versus political appointees is at a low of 55%, according to the American Foreign Service Association, the Foreign Service union. There are also no career Foreign Service officers serving as an Assistant Secretary of State, although the top diplomat for Africa is a retired Foreign Service officer and at least three other positions are filled by Foreign Service officers in an acting capacity.

ABC News's Ben Siegel contributed to this report.