Pauline Hanson has secured a six-year Senate term, while Derryn Hinch has only three years before he faces re-election, under a deal struck by the major parties.

Senators are usually elected for six years at a time, but the July 2 double dissolution election put the fate of all 76 senators on the line.

A normal election sees only half the Senate face voters, with the exception of the ACT and Northern Territory, whose two senators each are up for re-election at every federal poll.

Cabinet Minister Mathias Cormann told Sky News the first six senators elected in each state will get six-year terms.

"Under the methodology used so far, the first six senators elected would get six years, whoever they are and whoever they represent," Senator Cormann said.

When pressed about whether minor party senators would be unfairly disadvantaged, he said the outcomes varied in different states.

The Opposition intends to back the move, ensuring it will be endorsed by the Senate.

Labor's Senate leader Penny Wong said: "Labor will support the Government's proposal to allocate senators' terms of office according to the order in which Senators were elected in each state."

"This is consistent with the Senate's previous practice following double dissolution elections and reflects the will of the voters."

There had been speculation about how the major parties would decide on the Senate terms.

There are two methods of allocation available — the "recount method" and the "order-elected method".

The latter method, which has been adopted by the Coalition and Labor after this year's poll, sees the first six senators elected in each state receive the longer terms, and the rest given three years in the Upper House.

In both 1998 and 2010, the Senate voted in favour of using the recount method following future double dissolutions.

That means Senator Hanson could lead her One Nation Party in the Senate for the next six years, alongside other crossbenchers, including South Australians Nick Xenophon and Stirling Griff from the Nick Xenophon Team and Tasmania's Jacqui Lambie.

Senator Hinch had pushed for the "recount method", arguing it would deliver a fairer result.

"The Government, of course, and the Labor party have decided no, they'll go the other way, and so yes, I have to face the polls again in three years," Senator Hinch told Radio National.

He had previously threatened legal action if he was pushed to take a half-Senate term.

"I'm not going to take legal action, I'd rather save the money for my re-election campaign," Senator Hinch said.

"Once I went through it all and talked to lawyers about it, it's not a constitutional issue, so I haven't got a legal leg to stand on, it's a Senate issue and [Senator] Cormann and [Senator] Wong are entitled to do this.

"I've got three years, if I don't do well in that three years, they're entitled to throw me out."

New South Wales Six years Three years Marise Payne LIB Concetta Fierravanti-Wells LIB Sam Dastyari ALP Doug Cameron ALP Arthur Sinodinos LIB Lee Rhiannon GRN Jenny McAllister ALP John Williams NAT Fiona Nash NAT Brian Burston ONP Deborah O'Neill ALP David Leyonhjelm LDP

Victoria Six years Three years Mitch Fifield LIB Jacinta Collins ALP Kim Carr ALP James Paterson LIB Richard Di Natale GRN Gavin Marshall ALP Bridget McKenzie NAT Derryn Hinch JP Stephen Conroy ALP Janet Rice GRN Scott Ryan LIB Jane Hume LIB

Queensland Six years Three years George Brandis LNP Claire Moore ALP Murray Watt ALP Ian Macdonald LNP Pauline Hanson ONP Larissa Waters GRN Matt Canavan LNP Barry O'Sullivan LNP Anthony Chisholm ALP Chris Ketter ALP James McGrath LNP Malcolm Roberts ONP

Western Australia Six years Three years Mathias Cormann LIB Patrick Dodson ALP Sue Lines ALP Linda Reynolds LIB Scott Ludlam GRN Chris Back LIB Michaelia Cash LIB Louise Pratt ALP Glenn Sterle ALP Rodney Culleton ONP Dean Smith LIB Rachel Siewert GRN

South Australia Six years Three years Simon Birmingham LIB Anne Ruston LIB Penny Wong ALP Alex Gallacher ALP Nick Xenophon NXT David Fawcett LIB Cory Bernardi LIB Skye Kakoschke-Moore NXT Don Farrell ALP Sarah Hanson-Young GRN Stirling Griff NXT Bob Day FFP