The bipartisan backing for Ukraine in its long face-off with Russia has been a hallmark of Congress’ role in foreign policymaking for decades. Congress — both parties — has generally been willing to confront Moscow more forcefully over its treatment of Ukraine than the Trump, Obama or George W. Bush White Houses.

But with U.S. policy toward Ukraine the centerpiece of the impeachment inquiry, President Donald Trump’s antipathy toward Kyiv out in the open, and Republicans not wanting to break with their GOP president publicly over Ukraine policy, concern is rising that this longstanding bipartisan consensus to keep Ukraine inside the Western European camp could erode.

Indeed, the career diplomats and military officers who have given depositions to the House Intelligence Committee in the past several weeks said — separate from any presidential misconduct — that they feared if Ukraine’s new president did Trump’s bidding and announced an investigation of Democratic presidential candidate and former Vice President Joe Biden and his son Hunter, that it would do precisely that — kill the bipartisan support for Ukraine in Congress.

[Impeachment news roundup: Nov. 7]

So far, the consensus on Ukraine in Congress seems largely to be holding, at least publicly, through lawmaker endorsements for continued military and economic assistance to Kyiv.

But on the less-tangible forms of support that Congress provides to Ukraine, such as oversight hearings of administration foreign policy, co-signing letters of support on Ukraine-related issues, or pressing for language in spending bills that require the State and Defense departments to spend foreign aid on Kyiv, there are signs of a partisan split.

Former officials, lawmakers and staffers said strong agreement remained that the foreign assistance that Congress provides to Ukraine, hundreds of millions of dollars in annual military and economic aid, is not in jeopardy.

Senate Armed Services Chairman James M. Inhofe, R-Oklahoma, a longtime advocate for providing lethal military assistance to Ukraine, said he sees “absolutely no connection” between Congress’ traditional support for Ukraine and the impeachment investigation.

Added Sen. Lindsey Graham of South Carolina, the lead Republican on the Appropriations subcommittee with responsibility for foreign assistance: “I am for Ukraine. I am not going to let this color my view that it’s in our strategic interest to stand with the people of Ukraine.”

Sen. Jeanne Shaheen of New Hampshire, the top Democrat on the Senate Foreign Relations Eurasia subcommittee, said she also thinks lawmakers can distinguish between their traditional support for Ukraine, and the polarizing debate surrounding Trump’s actions toward the country.

“To date, the support for Ukraine has been very bipartisan,” she said. “Most of my colleagues who I’ve talked to appreciate that it’s in America’s interest to have a Ukraine that’s westward-looking, that isn’t under the influence of Russia and that can stand on its own.”

“The bipartisan support that Ukraine enjoys on Capitol Hill is one of its strongest international calling cards,” said Nina Jankowicz, a fellow at the Wilson Center specializing in disinformation and Eastern Europe and who has spent considerable time in Ukraine.

If perceptions take hold that Congress is no longer as united in its support for Ukraine, European allies could conclude that it is acceptable for them to also walk away from Ukraine, she said. Similarly, Russia would likely interpret it to mean it will have a freer hand interfering in Kyiv’s internal affairs and consolidating its territorial hold over the eastern part of the country.

Fears of loss of bipartisan support

Fears that Trump was putting at risk bipartisan congressional support for Ukraine by pressing newly elected Ukranian President Volodymyr Zelenskiy to publicly announce political investigations into the Bidens were at the heart of the objections that multiple U.S. government officials raised in their depositions before the three House committees investigating the scandal.

“I realized that if Ukraine pursued an investigation into the Bidens and [Ukranian gas company] Burisma, it would likely be interpreted as a partisan play which would undoubtedly result in Ukraine losing the bipartisan support it has thus far maintained. This would all undermine U.S. national security,” said Army Lt. Col. Alexander Vindman, the National Security Council’s top Ukraine expert, in his late October opening statement to the House committees about what he witnessed of Trump’s shadow foreign policy toward Ukraine, which was run through Rudy Giuliani, personal attorney to the president.

Acting U.S. ambassador to Ukraine William Taylor testified he told the Ukrainian president in mid-September, just days before Trump lifted the hold on the security assistance, that he would endanger bipartisan congressional support for his country if he undertook the investigations requested by Trump and Giuliani.

“I had just said to President Zelenskiy, bipartisan support of Ukraine in Washington is your most valuable strategic asset, don’t jeopardize it,” the longtime diplomat said, according to a transcript of his deposition released on Wednesday.

Taylor also testified that Sens. Ron Johnson, R-Wisconsin, and Christopher S. Murphy, D-Connecticut, echoed the same sentiment in their own early September meeting in Kyiv with Zelenskiy.

“My recollection of the meeting is that both senators stressed that bipartisan support for Ukraine in Washington was Ukraine’s most important strategic asset and that President Zelenskiy should not jeopardize that bipartisan support by getting drawn into U.S. domestic politics,” Taylor said.

Zelenskiy’s government largely heeded the chorus of warnings about the risks of appearing to take sides in U.S. domestic politics, but bipartisan support for Ukraine could still ultimately be weakened, U.S. policymakers warn.

That’s because Trump — angry and fearful of the potential damage done to his reelection prospects by the growing Ukraine scandal — could lash out at any bipartisan efforts to override his Ukraine policies, seeing in them a rebuke from Republicans.

And GOP lawmakers, leery of being on the receiving end of a Trump Twitter tirade, have repeatedly signaled they don’t want to conduct oversight of administration actions that may have militarily and politically weakened Ukraine.

“I hope Congress takes a look at the big issues about the management of our foreign policy that are implicated in the current situation — from how money is spent, to the role of ambassadors, to proper oversight — so as to have a salutatory impact on a better U.S. policy going forward, rather than just focusing on partisan sniping,” said Lester Munson, a former Republican staff director on the Senate Foreign Relations Committee, now vice president of international affairs at BGR, a lobbying firm.

Lindsey McPherson contributed to this report.