A former counsel to Ronald Reagan’s White House, who helped vet Sarah Palin as John McCain’s running mate and clear Mike Pence to be vice-president, has been chosen to fill the long-vacant role of US ambassador to Australia.

Arthur B Culvahouse Jr, referred to in the US press as “AB” and known for his firm’s work in vetting potential vice-president candidates for the Republican primary winners – including Donald Trump – has been named by the president as the new US envoy.

The diplomatic post has remained empty since John Berry finished his term in 2016. At the start of this week the US, under Trump, had diplomatic postings vacant in 18 countries – including Australia.

Admiral Harry Harris, who had been welcomed by the then foreign minister Julie Bishop and the former prime minister Malcolm Turnbull as “a really good friend”, was diverted to Seoul earlier this year, shortly after he was appointed to fill Berry’s shoes.

Bob Corker turned down the role in March to concentrate on his career in the US Senate.

The lack of an ambassador had become a joke in Canberra’s diplomatic circles but, on the eve of crucial US midterm elections, the White House announced that the president intended to nominate for three vacant positions, including the Australian ambassador role.

Culvahouse was awarded the Presidential Citizens medal in 1989, before adding the Defense medal for distinguished public service to his trophy case from the then secretary of defense, Dick Cheney, in 1992.

The White House statement said the Tennessee native had led the international law firm O’Melveny and Myers.

The appointment still has to be approved by the US Senate.

Australia’s foreign affairs minister, Marise Payne, has been contacted for comment.

The federal opposition has reacted positively to the appointment. The acting shadow foreign affairs minister, Mark Dreyfus, noted Culvahouse had “an extensive career in law and advising the US government”.

“America is one of Australia’s closest friends and staunchest allies,” Dreyfus said. “This relationship has been one of the central pillars of Australian foreign policy since the end of the second world war and will remain so into the future.

“Labor looks forward to continuing to work closely with the US to advance bilateral ties and our mutual interest in peace and stability in our region.”