Bombshell defection boosts Labor's majority in Senate

The defection represents a further setback for the Greens after losing three seats at the federal election, with Senator Cox only informing party leader Larissa Waters about an hour prior to the announcement.

The Yamatji-Noongar woman was elected to the upper house in 2021 to fill a Greens vacancy and had been the party's Indigenous affairs spokesperson.

Despite having last year suggested the Albanese government was "not interested" in closing the gap between Indigenous and non-Indigenous Australians, Senator Cox said she felt her values and priorities were better aligned with Labor than the Greens.

"I've worked hard to make Australia fairer and much more reconciled, but recently, I've lost some confidence in the capacity for the Greens to assist me in being able to progress this," she told reporters.

"I feel reassured with my experience, my skills and my knowledge, I can continue to collaborate and build on the existing relationships with an already amazing team of Labor MPs across the country."

Senator Waters said the party was disappointed but wished Senator Cox well.

"Senator Cox has said that her values align with the Labor party. This is the same Labor party who this week approved the climate wrecking North West Shelf gas project, which UNESCO advises will destroy significant First Nations heritage and ancient rock art," she said in a statement.

"Senator Cox would have had more chance of effecting change by continuing to work with the Greens in the sole balance of power."

Senator Cox, who was a member of the Labor Party before joining the Greens, will be formally admitted into Labor on Tuesday.

She was not required to run in this year's federal election as she was elected for a six-year term in 2022.

Mr Albanese said Senator Cox, the first Indigenous woman to represent WA in the upper house, had approached him about the switch and would be a welcome addition to the government benches.

"She wants to be part of a team that's delivering progress for this country by being a part of a government that can make decisions, to make a difference," he said.

"Dorinda Cox is someone who's a former police officer. She's someone who has a lot to offer in terms of policy development."

Senator Cox was accused of bullying Greens staffers in 2024, with as many as 20 employees leaving in three years and complaints made to parliament's workplace support service.

Mr Albanese said the allegations had been examined.

"They were all dealt with in Senator Cox's case and dealt with appropriately," he said.

Senator Cox said improvements for Indigenous people would be more achievable within the government than from the crossbench.

"I made that (decision) based on some deep reflection," she said.

"It was one that I considered both at a professional level, but also at a personal level. So this wasn't a decision that I did on the hop or based on emotion."

Senator Cox last week spoke out against the Albanese government's decision to allow Woodside to continue operating its North West Shelf gas project until 2070.

Pressed on her previous opposition to the project, Senator Cox said she did not want to comment on the issue as the extension was still being provisionally approved.

Senator Cox last year accused the Albanese government of being complicit in "war crimes" carried out by Israel in Gaza.

Labor still requires the support of either the Greens or the coalition to pass legislation despite gaining a 29th senator.