The idea of merging South Australia and the Northern Territory, creating the new state of Centralia, has been raised again, with some support from former Territory and federal MPs.

Former deputy prime minister and Nationals leader Tim Fischer is on board, backing recent comments from former NT Attorney-General John Elferink.

But with the Territory economy in crisis, the concept is unlikely to attract much interest in SA, especially from the current Liberal administration.

Australian Conservatives Senate candidate Rikki Lambert says the idea is an interesting one and not without merit.

He says SA Premier Steven Marshall should explore the proposal but only on South Australia's terms.

At the moment, Mr Lambert says, the terms are not really attractive to SA.

"You have a jurisdiction that is effectively broke wanting to join a South Australian jurisdiction that is only just coming off of the dependence on state spending that we saw under Labor," he said.

But Mr Fischer said he strongly supported the idea of a merger which would help Australia capitalise on the opportunities presented by the transcontinental railway that now linked Adelaide and Darwin.

He told AAP a merger would bring a "dynamic economic focus" to the new state.

Mr Elferink has suggested repealing the NT's self-government act to create the new state of Centralia.

He said the merger would have the resources to rival Western Australia and would help boost Australia's trade with Asia.

His plan comes at a time of economic turmoil in the Top End with the Labor government's recent admission that its finances are so bad it is borrowing money to pay public service wages and interest on its debt.

A report on budget repair called for public service cuts but the government has ruled out taking a "slash and burn" approach to public sector jobs.

It has called for public comment and help, including input from industry and unions.

Former South Australian premier Jay Weatherill was keen to forge closer economic and cultural ties with the Territory, meeting with Chief Minister Michael Gunner a number of times to progress those aims.

But the new SA government under Mr Marshall is expected to be less enthusiastic about the idea of significantly closer links.

Current SA Opposition Leader Peter Malinauskas was in favour of exploring a merger in his previous role as a union leader.

"But if it's going to be pursued, it needs to be done with the support of both the population of the Northern Territory and the South Australian community," Mr Malinauskas said.

Business SA boss Nigel McBride also liked the idea back in 2015, with it offering local companies a "real gateway to Asia".