Labor is expected to endorse former NSW premier Kristina Keneally to replace resigning senator Sam Dastyari.
The Australian reported on Wednesday the two strongest potential contenders, unions bosses Tony Sheldon and Tara Moriarty, would not be standing for the position.
That would leave Ms Keneally contesting the post against two former state MPs, Virginia Judge and Barry Collier.
She posted a statement on Wednesday evening expressing her desire to fill the vacancy left by Dastyari.
"I have today indicated to the Labor Party my interest in the Senate vacancy," she said in the statement.
"Over the coming days I will be speaking with rank and file members of the NSW ALP and affiliated trade unions to the Labor Party to seek their support."
NSW Labor secretary Kaila Murnain told AAP nominations would formally open next week and close on February 1, and the party's administrative committee would confirm who fills the vacancy the following day.
Mr Dastyari announced he was quitting politics late last year amid scrutiny of his dealings with a Chinese businessman and political donor.
Sky News reports Mr Dastyari is still drawing a salary of more than $200,000 a year as a Senator after announcing his intention to resign on December 11.
Transport Workers Union national secretary Tony Sheldon had been mentioned as a possible candidate.
NSW Health Services Union calls for fresh blood instead of Kristina Keneally as Labor's replacement for Sam Dastyari's upper house seat. Source: AAP
However Mr Sheldon told reporters on Wednesday: "I have not put my name forward at this point to make a formal nomination.
"My concern ... is to make sure our roads are safer and fairness is delivered in workplaces," he said.
Comment was being sought from Tara Moriarty, secretary of hospitality union United Voice and the fifth-placed candidate on Labor's NSW ticket in 2016.
Ms Keneally failed in her bid to take the seat of Bennelong in a December by-election.
But Labor sources says she has been keen for some time to move to Canberra.
