Joe Hockey will be leaving his post as Australian Ambassador to the US as storm clouds from the Trump administration threaten the solid, longtime relationship between the two allies.
The former Australian treasurer, who took up the Washington DC post three years ago, has helped keep the US-Australian alliance together following Donald Trump's 2016 election win while other allies - including Canada, the UK and Germany - have fallen out of favour with the president.
Mr Hockey will return to Australia in January when his term ends, according to diplomatic sources.
He is expected to take a job in the private sector.
Mr Hockey has been able to successfully build a relationship with the unconventional Mr Trump better than any other diplomat in Washington DC, with invites to at least two golf games with the president and guiding Australia away from minefields including the steel and aluminium tariffs slapped on almost every nation.
"We are not judgmental about the Trump administration," Mr Hockey told AAP earlier this year.
"I think that is what separates us from everyone else."
It was golf and Mr Hockey's contact book that first gave Australia an edge after Mr Trump's surprise election win over Hillary Clinton.
The Turnbull government did not have a phone number for Mr Trump to make the traditional congratulatory call.
Mr Hockey scrambled and reached out to Australian golf great Greg Norman to get the president-elect's number.
"Well, Greg Norman is a mate of mine," Mr Hockey later said.
There was also that difficult call a week after Mr Trump moved into the White House when Malcolm Turnbull reminded him about the asylum-seeker deal.
The call was scheduled to last an hour, but Mr Trump cut it off after 25 minutes.
Mr Hockey was forced to rush over to the White House to repair the relationship.
If Bill Shorten leads the ALP to victory he will have to walk a careful path with the thin-skinned president.
Mr Shorten has previously called Mr Trump "barking mad".
Australia's good standing with Mr Trump could fall apart in coming months with the president and Republican allies vowing to expose the FBI's motivation for its investigation into the Trump election campaign and potential links to Russia.
Australia's former high commissioner to the UK Alexander Downer has been credited for being one of the sparks for the investigation.
Mr Downer claimed former Trump aide George Papadopoulos, over drinks in London in May, 2016, told him Russia had "damaging" material on Ms Clinton and might use it in the lead-up to the election.
