Prime Minister Malcolm Turnbull arrives back in Canberra early on Monday, after a whirlwind visit to the US to celebrate 100 years of mateship.
Mr Turnbull declared his visit to Washington DC a success after "frank and productive meetings" with President Donald Trump, military leaders, business executives and more than 40 state governors.
Mr Turnbull and his wife Lucy departed the US for Canberra on Sunday morning AEDT.
He'll have a new mate beside him on the frontbench when the Nationals elect a leader to replace Barnaby Joyce, who quit the role and the deputy prime ministership on Friday.
The government is hoping Mr Joyce's decision, after a fortnight of political and media attention over his extra-marital affair with a staffer, will be a circuit breaker.
A Sky News/ReachTEL poll on Sunday had Mr Turnbull's and the government's approval ratings slipping on the back of the Joyce affair.
The new Nationals leader and deputy prime minister is expected to be little-known Veterans Affair Minister Michael McCormack, who'll probably be asked about the coalition deal with the government at his first question time.
The federal opposition is also still interested in whether Mr Joyce breached any ministerial standards, or expenses guidelines, over his affair with Vikki Campion, who is pregnant with their child.
Labor will also exploit the battle between former prime minister Tony Abbott and his former cabinet colleagues. They expect Mr Joyce to follow suit.
The outspoken MP has promised not to "snipe" from the backbench.
"They will be like Statler and Waldorf from the Muppet Show, the government's greatest critics, trying to bring Malcolm Turnbull and the government down," Labor frontbencher Jason Clare said.
The former prime minister has used the parliamentary break to criticise ministers over their support for higher migration, and says the Joyce affair has been poorly managed "at the most senior levels of government".
Meanwhile, Senate estimates hearings will probe ministers and senior officials from government agencies and departments.
Malcolm Turnbull lauds US trip as 'very valuable'
Turnbull has declared his visit to Washington DC a success after "frank and productive meetings" with US President Donald Trump, military leaders, business executives and more than 40 state governors.
Mr Turnbull and his wife Lucy departed the US for Canberra on Saturday (Sunday morning AEDT).
They gave Mr Trump and first lady Melania RM Williams boots as gifts during Friday's four-hour visit at the White House.
Ms Turnbull also gave Ms Trump a scarf made by a small business located in the Wentworth electorate.
"This has been a very, very valuable visit," Mr Turnbull told reporters on Saturday before leaving for Maryland's Andrews Air Force Base and the long flight home.
"Our goal was to broaden and deepen our enduring relationship with the US, our great alliance, build on 100 years of mateship for 100 more."
Mr Trump told Friday's White House press conference he would "love" the Australian Navy to join US freedom of navigation patrols in the South China Sea.
A day later Mr Turnbull declined to rule out granting Mr Trump's wish, a move that would anger China.
"Australia, as you know, defends the right of freedom of navigation and overflight throughout the world but we do not want to speculate on operational matters," Mr Turnbull said.
Mr Turnbull said he did make a compelling case to Mr Trump that Australia should not be hit by any hefty tariffs on steel and aluminium imports into the US.
Mr Trump reportedly wants to introduce a global tariff of 24 per cent on steel and 10 per cent on aluminium imports.
"We believe we have made a very compelling case, but obviously the administration has to finalise its decision in this area," Mr Turnbull said.
The prime minister's last stop on his four-day visit to Washington DC was accompanying NSW Premier Gladys Berejiklian, Queensland Premier Annastacia Palaszczuk, Victorian Premier Daniel Andrews, West Australian Premier Mark McGowan, ACT Chief Minister Andrew Barr and Northern Territory Chief Minister Michael Gunner to the National Governors Association Winter Meetings.
It is the annual meeting for the governors of US states.
The prime minister told the governors America's leadership in the world was in the interest of both nations.
The Australian premiers and chief ministers also took turns addressing the large ballroom and promoting their states and territories.
