(CNN) Expert after expert in the House impeachment inquiry into President Donald Trump testified about one key fact: That Ukraine had no role interfering in the 2016 elections to help Hillary Clinton. And one key witness sounded the alarm even louder.

"This is a fictional narrative that has been perpetrated and propagated by the Russian security services themselves," said Fiona Hill , Trump's former top Russia adviser, in testimony that reflects what US intelligence officials have privately told lawmakers in recent months.

But to House Republicans, that's all just a bunch of talk.

Asked after Hill's testimony if he believed Ukraine interfered in the 2016 elections, House Minority Leader Kevin McCarthy said: "I think they did."

McCarthy is hardly alone. Amid the impeachment fight where Trump is demanding loyalty from congressional Republicans, most are unwilling to break from the President -- even on a matter that national security experts warn could help Russia in its efforts to undermine Ukraine.

Moreover, US intelligence officials who briefed senators in recent months have reiterated the point that Russia has been engaging in a years-long effort to shift the blame of Moscow's interference in the 2016 election to Ukraine, a message that has been echoed during public testimony by Hill and other witnesses in the impeachment inquiry.

But even Republicans who have sat for the closed-door depositions before the impeachment probe refuse to accept the notion that Ukraine had no role in interfering in 2016. And asmid Trump's continued criticism of the country, some won't even accept the idea that Ukraine is a "key strategic ally."

"OK, suddenly they're a key strategic ally?" said Rep. Scott Perry, a Pennsylvania Republican who sits on the House Foreign Affairs Committee and participated in numerous depositions in the impeachment inquiry. "I never heard that before the last eight weeks -- never heard that Ukraine was a key strategic ally."

Perry added: "I'm not disputing that they are a key ally and a strategic ally, but it's just interesting how you phrase that in this context like they can't survive without a White House meeting."

Witnesses in the impeachment probe testified that Trump and his lawyer Rudy Giuliani sought to grant a key White House meeting -- that the new Ukrainian administration viewed as critical to bolster its legitimacy in its fight against Russian aggression -- in exchange for Ukraine announcing an investigation into any role it had in the 2016 US elections as well as a probe into former Vice President Joe Biden and his son, Hunter Biden. Moreover, several witnesses also said that roughly $400 million in security assistance to Ukraine appeared to be held up until the investigations were announced publicly.

If Republicans began to accept the belief among national security experts in the US government that Ukraine had no role in 2016, they would further isolate Trump and underscore the notion that he is embracing a conspiracy theory. Yet few Republicans see things differently than the President.

"I do think there is ample evidence of Ukraine having engagement and involvement with things talking about a 2016 election," said Rep. Chip Roy, a Texas Republican who sits on the House Oversight Committee and sat through some of the closed-door depositions in the impeachment inquiry. "So, I think there is more than enough evidence on that."

Told about Hill's testimony that such a theory bolsters Russia's case, Roy shot back: "In what kind of universe, in what universe are these things mutually exclusive?"

In a briefing for senators this fall that closely aligned with witness testimony before the House Intelligence Committee, senators were told that the Russian disinformation operation focused on a handful of Ukrainians who openly criticized or sought to damage Trump's candidacy -- efforts that were significantly less organized than the multi-faceted election interference push ordered by Vladimir Putin, one US official said.

US intelligence officials also told lawmakers that Russia used intelligence operatives to spread now debunked conspiracies, along with established facts, to frame Ukraine for the interference in the 2016 campaign, the official said.

Russian intelligence officers conveyed that information to prominent Russians and Ukrainians, including oligarchs, to pass along to US political figures and some journalists who likely were unaware of where it came from, according to the same official.

Yet during the impeachment hearings, Republicans on the House Intelligence Committee continued to embrace Ukraine's role.

"Look, we all know that Russia meddled in the election," Ohio Rep. Jim Jordan told CNN after the Thursday hearing. "But that's not to say that Ukraine didn't try to influence the election."

During two weeks of hearings, Ukraine's alleged role was a constant refrain for the GOP.

"What is the full extent of Ukraine's election meddling against the Trump campaign in 2016?" California Rep. Devin Nunes, the ranking Republican on House Intelligence, said at Tuesday's impeachment hearing, citing one of the questions he says Republicans want answered.

Some of the accusations against Ukraine are outright conspiracy theories, such as Trump's baseless claims about a CrowdStrike and the Democratic National Committee server that he personally asked the Ukrainian President to investigate related to the 2016 election.

Trump's interest in CrowdStrike and the DNC server is part of a conspiracy theory that it was Ukraine, and not Russia, that meddled in the 2016 election. The idea is that there's a server from CrowdStrike, the company that investigated the hacked emails for the DNC, hidden in Ukraine, because the FBI examined CrowdStrike's "imaged" servers, which is a direct copy. But that's the FBI's official guidance of investigating cybercrime — it's faster and it doesn't require victims to completely halt their operations while the FBI takes months, or possibly years, to return those servers.

The other unsubstantiated allegation is that CrowdStrike is a Ukrainian company, even though its co-founder, Dmitri Alperovitch, is in fact Russian.

Other claims related to Ukrainian election meddling surround allegations about Democratic National Committee contractor Alexandra Chalupa. Nunes raised Chalupa's name repeatedly in the impeachment hearings, saying she "worked with Ukrainian officials to provide dirt on the campaign," which he contended was later provided to the DNC and Clinton campaign.

Chalupa was referenced in a January 2017 Politico article alleging she met with Ukrainian officials to provide opposition research on former Trump campaign chairman Paul Manafort's work in Ukraine.

Chalupa, however, denied the allegations in 2017 . "During the 2016 US election, I was a part time consultant for the DNC running an ethnic engagement program," Chalupa said in a lengthy statement to CNN. "I was not an opposition researcher for the DNC, and the DNC never asked me to go to the Ukrainian Embassy to collect information."

Hill's testimony Thursday also made a point to note that the Politico story made a specific distinction that various officials from Ukraine opposing Trump did not represent any "top-down" effort like Russia's systemic interference campaign.

Republicans have also cited an op-ed from the Ukrainian ambassador to the US, Valeriy Chaly, which criticized Trump during the 2016 election. Hill called that op-ed "ill-advised" and said she can't blame Trump for being aggrieved by the criticism.

But she noted Trump hasn't had the same reaction to other countries that have criticized him as he has toward Ukraine.

"I'm sorry to say that awful lot ... of senior officials in many governments, including our allied governments, said some pretty hurtful things about the President," Hill said.

"Now the difference here however is that that hasn't had any major impact on his feelings towards those countries. Not that I have seen. But I've heard the President say ... that 'Ukraine tried to take me down.'"

Indeed, Trump reiterated that refrain on "Fox and Friends" on Friday.