The last thing Canberra wants is to be drawn into the most vicious partisan dispute of its most important ally.

But now, it's connected to two of them.

A phone call has dragged Australia into the centre of America's unfolding impeachment drama and the completed — but not forgotten — Russia probe.

The news that US President Donald Trump asked Prime Minister Scott Morrison to coordinate with Attorney General William Barr to investigate the origins of the Mueller inquiry comes at a particularly explosive time.

A week ago, House Speaker Nancy Pelosi launched an impeachment inquiry after revelations of a different phone call — this one between Trump and his Ukrainian counterpart.

After discussing military aid with Volodymyr Zelensky, Trump said that he'd like a favour: the investigation of the Democrats' leading 2020 candidate, Joe Biden.

Trump's critics have been quick to draw on what they see as similarities with the Ukraine phone call that sparked the impeachment inquiry and the call with Australia.

Impeachment could be partisan quicksand that Australia will want no part of — and Canberra is acutely aware of this.

"Australia's always been willing to cooperate with a properly constituted US justice inquiry, and will do so," an Australian government source told the ABC.

"But recognising it's a highly partisan affair, we don't go into it with any great enthusiasm."

There are two big differences between the Ukraine and Australia calls

Democrats will likely point to Trump's call with Morrison as evidence that he has used the power of his office to further investigations that help him politically.

There are two big differences between the Australian and Ukrainian calls though.

One, there is no evidence or allegation that Mr Trump pressured Mr Morrison into some sort of "quid pro quo".

Two, the White House has been quick to hose down that this was a personal favour.

"This call relates to a [Department of Justice] inquiry publicly announced months ago to uncover exactly what happened," said Deputy Press Secretary Hogan Gidley.

"The DOJ simply requested that the President provide introductions to facilitate that ongoing inquiry, and he did so, that's all."

US President Donald Trump's phone call with Ukrainian President Volodymyr Zelensky has triggered impeachment proceedings against him. ( Reuters: Carlos Barria )

According to the White House, the call was just President Trump asking for help with a Department of Justice probe examining whether intelligence agencies overstepped the mark in launching the Mueller probe into potential 2016 election interference.

"I'm old enough to remember when Democrats actually wanted to find out what happened in the 2016 election," Mr Gidley said.

"The Democrats clearly don't want the truth to come out anymore as it might hurt them politically."

The context is impossible to ignore though. The unauthorised release of the call comes six days after an impeachment inquiry was launched.

For two years, some Trump supporters have suggested Alexander Downer's link to the creation of the Mueller report is conclusive proof Australia is part of a deep state conspiracy against Trump.

Depending on how the news of the phone call shakes out, some Democrats may see these revelations as conclusive proof that Australia is part of a deep state conspiracy against Mueller and in favour of Trump.

Love for Australia is a rare bipartisan agreement in America

Americans are torn on whether or not to impeach the President, with the latest polls showing the country tidily divided along partisan lines.

One thing they have is a uniquely united love for is Australia.

President Donald Trump hosted Scott Morrison at a State Dinner just last month. ( AP: Alex Brandon )

It's one of the joys of reporting here that Americans are always keen to hear about Australia.

Those conversations are usually followed by a lament about the long plane ride keeping them from visiting.

All of this news comes just weeks after Morrison's visit to Washington, when pictures of the two leaders side by side were beamed nationwide.

The access Australia has enjoyed has been remarkable, a testament to the hard work of the embassy team led by Ambassador Joe Hockey.

The challenge for Australia's clearly able diplomats will be ensuring that bipartisan affection is not threatened, and that both sides of politics maintain the love for down under.

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That will mean squashing the conspiracy theories and ensuring that the Canberra call doesn't become part of the American 'civil war' that is impeachment.