Labor senator Louise Pratt has announced she will retire from federal politics at the next election.
The West Australian won't seek preselection ahead of the vote, with her current term set to expire in 2025.
Senator Pratt, 51, who is Labor's deputy whip in the Senate, said she told Prime Minister Anthony Albanese earlier in 2024 of her intention to step down.
She added that health reasons had contributed to her decision.
"I do find zone changes, flights to and from Canberra harder than I used to, and it is getting harder and harder to get on that plane," she told reporters in Perth on Tuesday.
"I have psoriatic arthritis and it it much better managed when I'm not flying, not chairing estimates and not whipping in the chamber.
"I have literally spent ... three months in the air, 24 hours a day off the ground, so making this decision, nevertheless, has not been easy."
Senator Pratt was first elected to the Senate for Western Australia in 2008, after previously serving in the WA state parliament.
While she lost her Senate seat at the 2013 election, she was re-elected to the upper house in 2016.
Mr Albanese paid tribute to Senator Pratt's time in parliament, saying she had fought for multiple issues affecting people in the west.
"She's someone who has been an agitator, someone who has been out there pushing on issues, because she has wanted to make a difference each and every day," he said.
"Louise will be missed by her many friends and colleagues in the caucus.
"She is someone who will depart - not yet, in time, in July of next year - with enormous goodwill."
Senator Pratt said the early announcement of her retirement from politics would allow for Labor to preselect a new candidate in her place for the party's Senate ticket.
Foreign Minister and Leader of the Government in the Senate Penny Wong said the outgoing senator displayed courage and commitment during her time in parliament.
"Louise has always been a determined advocate with deep connections in the communities she represents," she said.
The next federal election must be held on or before September 27, 2025.
