Washington (CNN) When two key US allies -- the United Kingdom and Australia -- elevated conservative prime ministers, President Donald Trump didn't just see a diplomatic opening. He also saw a political one .

His new counterparts, Trump believed, could be persuaded to help him pursue a longstanding fixation: discrediting the Russia investigation. Trump raised the matter in telephone conversations with both Britain's Boris Johnson and Australia's Scott Morrison over the summer, according to people familiar with the calls.

Trump's cultivation of the newly installed leaders as potential associates in his political agenda reflects his intent at using foreign relationships to go after domestic rivals. It's continues a norm-breaking pattern of using fellow leaders to advance a partisan agenda . His actions came after Trump spent months quizzing aides, allies and friends if they thought the United Kingdom and Australia played a role in the origins of Russia probe, according to people familiar with the conversations.

Ahead of those discussions, Trump told advisers he believed he could convince the new leaders -- both viewed as more politically aligned with him than their predecessors -- to work with Attorney General William Barr as he sought information about the Russia investigation, multiple people later said.

Not only did he view the two new leaders as more cooperative to his position, he blamed both of their predecessors -- Theresa May and Malcolm Turnbull -- as partly responsible for the entire investigation, believing that under their leadership it was allowed to sprout, people familiar with his thinking said.

It's true that the United Kingdom and Australia were involved in the early stages of the FBI's Russia investigation in 2016, but there is no public evidence to support Trump's allegations that they were part of a politically biased conspiracy to undermine his campaign. Both countries are top US allies and routinely cooperate with US law enforcement and intelligence agencies. During the 2016 campaign, Australia and the UK passed along information to the US about suspicious ties between Trump campaign advisers and Russians.

Trump repeated his interest in the topic Wednesday.

"I've been looking at that long and hard, for a long period of time. How it started, why it started, it should never happen to another president, ever," he said during an East Room news conference with his Finnish counterpart.

After Morrison took office last year, and later as it became likely Johnson would succeed Theresa May at 10 Downing Street, Trump told associates he believed the men would prove more amenable than earlier leaders in helping provide information that might help discredit the Mueller investigation, according to the people familiar with the conversations.

That was due in part to their reputations as staunchly conservative populists, which Trump believed was a sign they would be more willing to help a like-minded leader. Trump was friendly with Johnson and had stated publicly even before May announced her resignation that he would make a strong UK leader.

As he learned more about Morrison, Trump grew similarly convinced the new prime minister -- who, like Trump, defied polls and ran on a hardline immigration message -- would prove open to his requests for help.

How receptive those leaders were to Trump's overtures isn't entirely clear. Morrison said Wednesday his call with Trump was a "fairly uneventful conversation" but suggested Australia was ready to cooperate with the US.

"I think it would have been quite extraordinary for us to deny such cooperation -- on what possible basis could we do that? We've got certainly nothing to hide," he told Sky News

Asked by a Labour lawmaker in Parliament Wednesday whether Johnson would ever "collude" with Trump, Foreign Secretary Dominic Raab said: "Of course neither the Prime Minister or the then-Foreign Secretary or any member of this government would collude in the way that he has described."

"That is of course entirely unacceptable, would never have happened and did not happen," he said, without denying Trump raised the matter with Johnson in the late-July phone call.

The White House also did not deny the issue was raised by Trump.

"World leaders need to be able to speak freely in their conversations with the President -- that is a key component to effective diplomacy. And that is why such conversations are kept confidential," press secretary Stephanie Grisham said. "We are not going to start discussing the contents of every conversation President Trump has with world leaders, other than to say his conversations are always appropriate."

Barr's Russia investigation review

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On Monday, an official familiar with Trump's phone call with Morrison said Barr has asked the President to request the help of several countries, including Australia, with a review of the early stages of the Russia investigation. That review is being led by US Attorney John Durham.

Justice Department spokesperson Kerri Kupec also confirmed that Trump, at Barr's request, has reached out to multiple other countries to ask them to assist Barr.

"At Attorney General Barr's request, the President has contacted other countries to ask them to introduce the Attorney General and Mr. Durham to appropriate officials," she said.

Barr traveled to London in late July for a meeting of the Quintet of Attorneys General and the Five Country Ministerial (FCM) of Public Safety Ministers. According to a Justice Department readout, he participated in meetings there with other senior Justice Department officials from July 28 to July 31. It's not known if he raised the investigation into the Russia probe origins in that meeting.

On Wednesday, Sen. Lindsey Graham, a top Trump ally in the Senate, sent letters to the prime ministers of Australia, Italy and the UK asking for continued cooperation with Barr.

"That the attorney general is holding meetings with your countries to aid in the Justice Department's investigation of what happened is well within the bounds of his normal activities. He is simply doing his job," he said.

Trump's conversations with foreign leaders have come under scrutiny after the release of a rough transcript showed Trump pushing Ukraine's leader to investigation former Vice President Joe Biden. The hopes he placed in Morrison and Johnson demonstrate yet another facet of his willingness to inject foreign policy with domestic politics.

Trump has long insisted the Mueller investigation originated from a corrupt "deep state" aided by foreign intelligence. After Trump granted Barr the authority to declassify certain information related to the origins of the Russia investigation, he specified part of the that effort should include looking into the UK and other countries who he claims may have been involved in nefarious activities meant to harm his election prospects.

"I hope he looks at the UK. And I hope he looks at Australia. And I hope he looks at Ukraine. I hope he looks at everything," Trump said. "Because there was a hoax that was perpetrated on our country."

In the run-up to Trump's trip June state visit to Britain, conservative pundits promoted those theories in hopes Trump would bring it up with British leaders, including then-Prime Minister May. Trump suggested there was a high probability he would raise the matter with his counterpart during their meeting at her offices in London.

"I may very well talk to her about that, yeah," he said. "There's word and rumor that the FBI and others were involved, CIA were involved, with the UK, having to do with the Russian hoax. And I may very well talk to her about that, yes."

'Utterly ridiculous'

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The notion Trump should raise the unsubstantiated claim during his meeting with his British counterpart did not appear to faze British officials, who acknowledged that meetings with the President often proceed in unpredictable directions.

"We heard what the President said, and if he raises it that's fine," one UK official said at the time.

Still, the answer to Trump's inquiries hasn't changed since the British intelligence agency took the extraordinary step in March 2017 to reject Trump's ideas as "utterly ridiculous."

"We would never get involved in a political campaign in the country of an ally," the official said. "We do not have anything to hide in this area."

Trump's baseless claims about UK spying into his campaign at the behest of his predecessor Barack Obama have rocked the special relationship between the two countries -- a relationship that includes extensive intelligence sharing.

Only months into Trump's presidency, then-White House press secretary Sean Spicer cited in a briefing an uncorroborated report alleging British involvement in an attempt to wiretap Trump Tower during the 2016 election. Later, British officials confronted him during a St. Patrick's Day reception at the White House to deny -- in serious and less-than-cordial terms, according to a UK official -- the allegations.

The British intelligence agency GCHQ released an exceedingly rare and pointed statement rejecting the claims as nonsense that "should be ignored," a sign that officials have said is evidence of the UK government's fury at the allegations the White House was lobbing.

But those denials and the evident anger coming from London did little to change Trump's view of the situation, which aides acknowledge is rooted more in Trump's deep resentments at the Russia investigation than any concrete evidence pointing to a British spying effort.

Those resentments only swelled following the release of former special counsel Robert Mueller's report, which did not establish a criminal conspiracy on the part of the Trump campaign to coordinate with Russia but nevertheless laid out numerous contacts between campaign officials and Russians.

A day after his on-again off-again state visit was finally announced in April, Trump tweeted a reference to the UK spying conspiracy, citing the far-right One American News Network.

"WOW!" Trump wrote. "It is now just a question of time before the truth comes out, and when it does, it will be a beauty!"