The Coalition is bracing for a factional battle over George Brandis’s vacant Senate seat, as Kristina Keneally appears to have successfully headed off a tightly contested preselection to enter the Senate.

The New South Wales Labor right is meeting on 30 January to work out a deal over who replaces Sam Dastyari in the Senate but the Australian reported on Wednesday that Keneally’s two main potential challengers have decided not to run.

Dastyari was forced to announce his resignation following revelations over his dealings with Chinese donors.

Meanwhile, in Queensland, where Brandis’s move to the UK high commission has left an opening, battle lines are emerging between the conservatives and the moderates over his replacement.

In January the secretary of the Health Services Union NSW, Gerard Hayes, made a public call for fresh blood to replace Dastyari. In comments suggesting he did not want Keneally to have a clear path, he said the party needed to “think broadly into the future as opposed to thinking about what we can do that’s easy” to represent workers’ interests.

Since then the Transport Workers Union national secretary, Tony Sheldon, and the United Voice NSW liquor and hospitality division secretary, Tara Moriarty, emerged as possible candidates, but the Australian reported on Wednesday both would not run.

That would leave Keneally contesting the post against two former state MPs, Virginia Judge and Barry Collier.

On Wednesday Sheldon told reporters in Sydney he had “been approached to nominate for the Senate and in previous years I’ve been approached to run for other political positions.

“My concern is exactly what I’m talking about today and is that our roads are safer.

“I have not put my name forward at this point to make a formal nomination … I haven’t made a decision about my nomination, or potential nomination, as yet.”

Dastyari was elected to a six-year term in the 2016 double dissolution election. As Jenny McAllister and Deborah O’Neill are not up for re-election either, the NSW right will also preselect a candidate in June to take top spot on the Labor ticket and be guaranteed a seat in the next half-Senate election.

Guardian Australia contacted Moriarty, who finished fifth behind Cameron and was not elected in 2016, and Sheldon for comment.

Brandis was also granted six years following the double dissolution 2016 election, which has added fuel to the preselection battle, with similar calls for “new blood”.

Some in the LNP are pushing for a woman to take the spot, as it attempts to tackle its gender imbalance. Former candidates Teresa Harding, Kerri-Anne Dooley, LNP Women president Theresa Craig and former senator Joanna Lindgren have all been named as potential contenders.

But all four women are known for their conservative beliefs, leaving moderates worried the spot will further undermine the LNP’s “small-l liberal” influence.

The former state MPs Tarnya Smith and Scott Emerson are also being touted as possible replacements, along with the former LNP adviser and campaign head Gerard Benedet.

“The state council need to be thinking long term about this,” a senior LNP source said. “Whoever it is will be there until 2022. Past the next election, where it doesn’t look like we are going to win. So if you take some high-profile losses there, [Peter] Dutton, [George] Christensen, who is your most senior Liberal in Queensland? But the moderates don’t have the numbers in the state council and haven’t since the merger. We need to make sure we don’t keep heading in the wrong direction.”

Nominations for the Queensland vacancy close on 29 January.