Sinodinos tapped for US role as Trump raises questions over Australia

Ahead of what could be a testing period for Australia's relationship with its most important diplomatic relationship, Senator Sinodinos - widely tipped to take a cabinet position in the re-elected Morrison government - will head to Washington.

The term of Joe Hockey, the current ambassador and former treasurer in the Abbott government, is to finish at the end of the year. This enabled Mr Morrison to offer the post to Senator Sinodinos who is expected to take over in January 2020, the start of a presidential election year.

Senator Sinodinos said he was pleased to take up the posting.

"I'm looking forward to the opportunity to serve my country abroad in this way," he said.

"This is a very good opportunity to regroup as a family after the health issues of recent years."

A highly respected former cabinet minister and chief of staff to John Howard, Senator Sinodinos served as Malcolm Turnbull's cabinet secretary but was forced to stand down to undergo treatment for non-Hodgkin lymphoma. He has since made a full recovery and was widely tipped to return to cabinet under Mr Morrison.

Senator Sinodinos, who will remain in the Senate until his posting, will walk straight into President Trump's concerns about the FBI investigation that led to the Mueller inquiry.

US Special Counsel Bob Mueller's report on links between the Trump campaign and Russia, pointed to a 2016 meeting between then Trump campaign aide George Papadopoulos and Australian then high commissioner to the UK, Alexander Downer, in a London bar as prompting the FBI to open its Trump-Russia probe.

The FBI probe led to Mueller being appointed as special counsel.

Ahead of a weekend trip to Japan, President Trump said he had declassified intelligence documents so the truth of the FBI inquiry could be determined.

"He can look and 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, because there was a hoax that was perpetrated on our country."

United States Studies Centre fellow Bruce Wolpe said Senator Sinodinos would be a fine appointment because of his experience and sharp political instincts.

He said they would come in handy given the move by President Trump to investigate the events of 2016.

"The trick will be engaging with President Trump and figuring out how to protect Australia's interests and dealing with a very transactional president," he said.

"The Mueller investigation is clearly in the mind of the President and how he thinks about the relationship. There is a big risk from Australia's perspective that in the future, if there is a request of President Trump, he's going to take into account the history of the relationship."

Mr Morrison would not be drawn on Mr Trump's comments or move, saying he would not comment on an investigation that was under way.

Senator Sinodinos focused on the close ties between the two nations.

"We are two of the world's oldest continuing democracies and have fought alongside one another in all the major conflicts of the last century. Above all we stand for humane and decent universal values," he said.