U.S. policy toward Ukraine is in shambles, lawmakers and foreign policy experts say, as House Democrats barrel along with an impeachment probe that began with an anonymous whistleblower’s complaint and has ballooned into the most serious threat so far to Donald Trump’s presidency.

"This is going to do lasting damage,” said Andrew Weiss, who headed up Ukraine policy on the National Security Council under President Bill Clinton. “For the last five years it was a given that the U.S. had Ukraine’s back,” he said. “Now that’s going to be far more complicated, with a lot more distrust and a lot more scrutiny."

The impeachment inquiry, now entering its second month, began after Democrats secured the release of an anonymous whistleblower’s complaint alleging that President Donald Trump had pressed Ukraine’s President Volodymr Zelensky to investigate his chief campaign rival on a July 25 phone call.

Officials in Kyiv are now wondering who they can trust in Washington—especially given the recent departures of several of their American interlocutors, including former special envoy Kurt Volker, former U.S. ambassador to Ukraine Masha Yovanovitch, and former senior director for European and Russian Affairs Fiona Hill.

Volker, along with ambassador to the European Union Gordon Sondland and Energy Secretary Rick Perry, was one of the self-dubbed “three amigos” who worked with Trump lawyer Rudy Giuliani to run what State Department officials have described as a shadow foreign policy that crossed ethical and possibly legal boundaries.

And the acting ambassador who replaced Yovanovitch, Bill Taylor, has just landed back in Kyiv after delivering explosive testimony that accused President Trump of leaning on Zelensky to investigate Joe and Hunter Biden and “get to the bottom” of Ukraine’s supposed interference in the 2016 election.

On Friday, President Trump attacked his own top diplomat in Kyiv -- Taylor, a Vietnam veteran who was first appointed ambassador by George W. Bush -- as a “Never Trumper.” Reminded that Pompeo had brought Taylor out of retirement after Yovanovitch was recalled from Ukraine, Trump said, "Everybody makes mistakes.”

Ukrainian officials have said publicly that nothing is amiss, but private accounts — including Taylor’s testimony, which detailed his interactions with his disturbed counterparts in Kyiv — have indicated otherwise.

One continuing source of anxiety in Kyiv is the military assistance aid Trump allegedly held up in an effort to pressure Zelenksy -- aid that was renewed when Taylor and lawmakers from both parties raised alarms inside the administration.

Some of President Trump’s closest allies on Capitol Hill have erupted in anger over the withholding of the security funds, even as they’ve complained that Democrats are running an illegitimate and unfair impeachment process.

In a continuing resolution to fund the government through November 21, Congress approved extending for another year $250 million in Ukraine Security Assistance Initiative funds that were set to expire on September 30. Trump signed the CR late last month, but Ukrainians are still apprehensive about the funds “going through without a hitch,” according to Andrij Dobriansky, a representative for the Ukrainian Congress Committee of America.

“Kyiv is in wait-and-see mode,” said Michael Carpenter, a former Pentagon official with responsibility for Russia and Ukraine under President Obama.

As Taylor noted in his opening statement, Ukraine remains in active hostilities with Russia. “Ambassador Volker and I could see the armed and hostile Russian-led forces on the other side of the damaged bridge across the line of contact,” Taylor said, recalling a trip to the front line in northern Donbass in July. “Over 13,000 Ukrainians had been killed in the war, one or two a week,” he continued. “More Ukrainians would undoubtedly die without the U.S. assistance.”

Several senior officials with a Ukraine portfolio have either testified in the impeachment probe or plan to do so are still in government, in addition to Taylor: Deputy Assistant Secretary George Kent; Acting Assistant Secretary for European and Eurasian Affairs Phil Reeker; Deputy Assistant Secretary of Defense for Russia, Ukraine and Eurasia Laura Cooper; and Tim Morrison, Hill’s replacement on the NSC.

Taylor is still carrying out his duties as usual, his lawyers told POLITICO. But Democratic Rep. Tom Malinowski, who sits on the House Foreign Affairs Committee, said he worries “there isn’t any energy” behind the default U.S. policy of support for Ukraine right now, “and that the remaining key actors are going to tread very carefully.”

John Herbst, a former U.S. ambassador to Ukraine and director of the Atlantic Council’s Eurasia Center, said he believes the basic process of formulating Ukraine policy, starting at the deputy assistant secretary and assistant secretary level at the State Department, DOD and the NSC and moving up the chain to the head of each institution is still in place.

But he singled out Volker’s focus on negotiating a settlement to the war in eastern Ukraine as an area of special concern, given the envoy’s sudden departure.

“One thing that requires constant attention is the Minsk process,” Herbst said. “Volker’s resignation is really unfortunate in that context, but I think steps are being taken now to replace him.”

The Minsk process refers to negotiations that have been underway since 2014 to end the war with Russian-backed separatists in the Donbass region of eastern Ukraine. Zelensky announced on Oct. 1 that he had signed on to the so-called Steinmeier formula, a German-led road map to ceasing hostilities that many in Ukraine reject as a capitulation to Moscow.

The Trump administration would not answer basic questions about where Ukraine policy stands now and who is in charge of it. Officials at the National Security Council and U.S. Embassy to the E.U. referred requests for comment to the State Department, which did not respond to multiple inquiries.

Secretary of State Mike Pompeo bristled this week at a local reporter’s questions about the impeachment hearings.

Asked what he did with a cable from Taylor expressing his concerns about what he described as the “irregular channel,” Pompeo said he was “not going to talk about [the] inquiry this morning” and reiterated that Democrats were not allowing State Department lawyers to sit in on depositions.

“It’s not fair,” said Pompeo, who is contemplating running for Senate in his home state of Kansas. “I get notes from people in Kansas all the time saying it’s not right, they think it’s unfair too.”

Daniel Fried, a longtime State Department official who travels frequently to Ukraine as a fellow at the Atlantic Council, said the Ukrainians “universally think it’s bad news that Volker left, because they trusted him. And who would take his job now, knowing there might be some backchannel undoing you?” (The Atlantic Council has taken money from Burisma, the Ukrainian gas company on whose board Hunter Biden once sat.)

Upon stepping down, Volker recommended a career officer with no previous involvement in Ukraine policy to replace him, according to a person with knowledge of the discussions.

That is primarily because Volker didn’t think it would be possible to convince someone outside government with relevant experience in Kyiv to take it on, this person said, and it’s not clear whether they’ve agreed to take the job.

“Nobody wants to touch” Ukraine policy now “given the political environment,” they said. “So it’s kind of a vacuum, which is terrible for Ukraine, and good for Russia.”

The vacuum in U.S. Eurasia policy extends all the way to Moscow, where departing ambassador Jon Huntsman has yet to be replaced by John Sullivan, the president’s proposed nominee. A confirmation hearing for Sullivan, currently the deputy secretary of state, has not yet been scheduled by the Senate Foreign Relations Committee, a committee spokesperson said.

William Burns, the president of the Carnegie Endowment for International Peace and a former deputy secretary of state, said that “a dysfunctional Ukraine” will be looked upon fondly by Russian President Vladimir Putin. “We’ve contributed to that as well, and Putin becomes one of the big winners.”

Nahal Toosi and Daniel Lippman contributed to this report.