"Father of reconciliation" and respected Indigenous leader Pat Dodson is set to enter federal parliament as a Labor Senator.

Key points: WA Labor senator Joe Bullock announced retirement over same-sex marriage on Tuesday

WA Labor senator Joe Bullock announced retirement over same-sex marriage on Tuesday Bill Shorten announces Yawura leader Pat Dodson as his preferred replacement

Bill Shorten announces Yawura leader Pat Dodson as his preferred replacement Former Labor senator Louise Pratt pulls out of race

Former Labor senator Louise Pratt pulls out of race Senior Labor source says Bullock's gay marriage stance an "invention"

Opposition Leader Bill Shorten held a joint press conference with Mr Dodson at Parliament House this morning to announce the Yawuru leader from Broome as his preferred candidate to take up a casual vacancy in the Senate.

The path has been cleared for him to enter the Upper House following the resignation of conservative senator Joe Bullock, who is standing down in protest over Labor's party position in favour of same-sex marriage.

Mr Dodson has admitted he left the Labor Party in the eighties and has considered himself non-aligned for many years.

But he said Mr Shorten picked up the phone to offer him the position in a surprise move, and after many years consulting with successive governments he wanted to make a difference from the inside.

"Having spent much of my adult life trying to influence our national conversations, debate, government and the parliament from the outside, it is now time for me to step up to the plate," Mr Dodson said.

"[It is time to] have a go at trying to influence those conversations, debates and public policies from the inside, as a member of the Senate and representing Western Australia."

Mr Shorten described Mr Dodson as as "truth teller" and said his decision to take up public office was a "win for Australia".

"He is a person of unmatched intelligence, integrity and achievement," Mr Shorten said.

"Nationally recognised and rightly admired as the father of reconciliation, a truth teller, a powerful advocate for recognition, justice equality and fairness for Aboriginal and Torres Strait Islander people."

Indigenous Affairs Minister Nigel Scullion has also welcomed the announcement and said Mr Dodson would bring a wealth of political and life experience into parliament.

"I would look forward to working with Professor Dodson in Parliament to further advance the interests of Aboriginal and Torres Strait Islander people," Senator Scullion said.

Second Indigenous Labor candidate in a week

Mr Dodson is the second high-profile Indigenous person to be tapped for a Labor seat in as many days.

On Tuesday the party announced that deputy New South Wales Opposition leader Linda Burney would contest a federal lower house seat at this year's election.

Mr Dodson is also related to sitting Indigenous Labor Senator Nova Peris.

Mr Dodson has been a key advisor to successive federal governments on Indigenous policy and was one of the commissioners on the Royal Commission into Aboriginal deaths in custody.

He was also the first Indigenous Australian Roman Catholic priest and is known as the "father of reconciliation" because of his role in driving the Council for Reconciliation.

His decision to take over the Senate seat means he will relinquish his role as one of the co-chairs of the council consulting on the best way to achieve Indigenous recognition in the Constitution.

Former Labor senator Louise Pratt was ousted to make way for Mr Bullock, and last night she indicated she was also interested in the casual vacancy created by his departure.

She has since pulled out of the race following this morning's announcement.

"Louise Pratt is an excellent senator and she's got a contribution to make," Mr Shorten said.

"On this occasion though, I'll support Pat Dodson."

Ms Pratt said she supported Mr Dodson, who "has the capacity and experience to make a significant contribution".

"I still have more to offer Western Australia and the country in public life, and hope to continue that in the future," she added.

Labor MPs say Dodson call has widespread support

West Australian federal Labor MP Alannah MacTiernan said she was confident Mr Dodson was widely supported in the party.

"Pat has been a great figure in West Australian and Northern Australian public life for so long, and there is an absolute recognition we need a diversity of voices in the Parliament," she said.

"We need strong, powerful Aboriginal voices and that's certainly what Pat can bring.

"There will be other opportunities for Louise Pratt, and indeed others as we are likely to be going into a double dissolution."

While she supported Mr Dodson filling the vacancy, Ms Pratt said she still had ambitions to re-enter Federal politics at some stage.

"I am considering my options but I would not expect that I would want to cause difficulties in terms of bringing more diversity into the Parliament," she said.

"Pat Dodson will make a terrific contribution to the Australian Parliament."

Bullock 'leaving before he is dropped'

A senior Labor source, who did not wish to be named, told the ABC Mr Bullock's comments about gay marriage were an "invention" because he was not going to be preselected again in the event of a double dissolution election.

The source said he was using the gay marriage stance as an excuse to leave before he was dropped.

"It's not a plausible explanation, it's just made up," they said.

"He knew where the party was heading. There was no way of him getting Senate preselection. The right asked him to leave, so he was factionally powerless.

"He would be at the bottom of ticket even if there hasn't been a double dissolution election."

The source said the conscience vote on the issue of gay marriage in 2019 would not have affected Mr Bullock.

"The date was set so all existing senators would not be required to vote, he knows that," they said.

WA Labor leader Mark McGowan and WA Labor Party secretary Patrick Gorman both declined to comment on Mr Bullock's departure.