Popular Tasmanian senator Lisa Singh is once again bearing the brunt of Labor's factional machinations, after being dropped to what's considered to be an unwinnable spot on the party's senate ticket.

It is understood Senator Singh received the second highest number of "rank and file" votes during preselection at the state Labor conference in Hobart, after left-aligned senator Carol Brown.

But after distribution of preferences and weighting (delegate votes are worth about three times that of "rank and file" votes), Ms Singh has been placed in fourth position on the ticket after Senator Brown, senator Catryna Bilyk and Australian Manufacturing and Workers Union state secretary John Short.

In 2016 Ms Singh was also dropped down the ticket, but retained her Senate seat after picking up more than 20,000 first preference votes in the double-dissolution election.

This time only half the Senate is up for re-election, meaning Senator Singh would need to double her "below the line" vote in order to be elected.

Ms Singh said she was disappointed but respected the process.

"This is obviously not the result I was wanting, I would have been happier to be much further up the ticket," she said.

Senator Singh said she was pleased with the support from "rank and file" members, but another Labor source told the ABC the senator should have viewed the "rank and file" vote as disappointing.

Lisa Singh says she has proved people wrong before and been elected from a bad ticket spot. ( ABC News: Alex Blucher )

Senator Singh, who is not aligned with either the left or right faction of the Tasmanian Labor party but is part of Labor left nationally, said she would campaign for a Bill Shorten Labor government, but was not clear on whether she would put her energy and finances into a campaign for "below the line" votes to be re-elected to the Senate.

She said she would take time out to consider what the preselection result meant for her.

"I think last time everyone said I was in an unwinnable position and we proved them wrong," she said.

"I need to take the time on where I find myself, take some time to talk to my family, my staff, with Labor members and supporters about what this means for the longer term."

She said she was bearing the brunt of negative aspects of the factional machinations of the Labor party.

"It's no secret that factional arrangements are put in place often in these types of preselections and when that happens and you're not part of that factional arrangement you can end up losing out," she said.

She thanked those in the community who had supported and campaigned for her previously.

"I think the result from last time showed the public weren't happy that I was placed last on the ticket last time so I'm sure they will make their voice heard again."

Senator Singh ruled out running as an independent.

Party stalwart slams preselection

Former Labor senator Margaret Reynolds has described the preselection process as un-democratic.

"Do you know of a job interview where you can lobby the preselectors? You cannot do that in a normal job interview," she said.

"I think the voters are sick of it, they are pretty fed up with politics anyway, especially at a federal level, and if they really understood what goes on behind the scenes they would be even more disgusted," she said.

Ms Reynolds said Senator Singh's popularity would have seen her strong votes flow to other candidates.

"Lisa was worth being number one on the Tasmanian senate ticket … But instead these deals are done and she is number four."

Ms Reynolds said the Australian Electoral Commission should take over running preselection of all political parties.

She said the current process was not based on merit.

"It's purely a numbers game," she said.

"Political parties sadly can't seem to help themselves … what we need is proper, transparent, professional preselections."