Veteran Labor frontbencher Jenny Macklin is retiring after almost 23 years in federal politics, making her the longest-serving woman in the history of the House of Representatives.

She was deputy to three Labor leaders — Kim Beazley, Simon Crean and Mark Latham — and held the key Families, Community Services and Indigenous Affairs portfolios in both the Gillard and Rudd governments.

In a statement, the member for the Melbourne electorate of Jagajaga said it was time for generational change.

"As the longest-serving Labor woman in the House of Representatives, ever, 'It's Time', as Gough so famously said, for me to move on," Ms Macklin said.

"It is time for me to spend more time at home, especially with our new grand-daughter.

"It's also time for the next generation. Although I still want to contribute to policy debates, it's time for me to step back."

Ms Macklin was a forceful advocate for the national apology to the Stolen Generations made by Kevin Rudd.

She was also one of the architects of the National Disability Insurance Scheme (NDIS) established by the Gillard government.

Ms Macklin was a key figure in the Gillard government. ( AAP: Lukas Coch )

The Labor frontbencher told ABC radio in Melbourne that while the NDIS was experiencing problems, it would prove transformative over time.

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"It's got a way to go yet, but I think in the end it will be revolutionary for people with disabilities," she said.

In 2012, Ms Macklin also weathered fierce criticism from welfare advocates after pushing thousands of single parents off their payment system, and onto less generous unemployment benefits.

The move was to save the Gillard government about $700 million, and Ms Macklin said the change would encourage more parents into the workforce.

But she later said Labor had "made a mistake", and the policy was too harsh.

Ms Macklin will step down immediately as Opposition spokeswoman for social services and go straight to the backbench.

She said that she wanted to maker sure the new shadow minister had time to get across the portfolio.

But her decision will force another mini-reshuffle of the Opposition's frontbench, creating a minor headache for Labor leader Bill Shorten.

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Mr Shorten heaped praise on Ms Macklin, saying she had "deep policy knowledge, unshakeable conviction and a ceaseless determination to see the right thing done".

"Every political party in Australia wishes they had a Jenny Macklin, but only Labor has been blessed with her extraordinary mind, her caring heart and her fearless love of the good fight."

Preselection powerplays and factional feuds

Ms Macklin's decision comes only one day after another Victorian Labor veteran, Michael Danby, also announced he would retire.

The retirements have inflamed internal Labor tensions, following a shift in factional allegiances in Victoria.

Adem Somyurek leads the so-called 'moderate Labor'. ( AAP: Julian Smith )

The ALP is facing both state and federal elections in Victoria in the next 12 months. The ABC understands there is a serious push from senior party powerbrokers for preselections to be decided by the national executive, rather than local ballots, to avoid party blood-letting.

The tensions come as a long-standing 'stability pact' between the right and left factions is tested.

During summer, a left-wing industrial sub-group, called the Industrial Left, split from the socialist left faction.

It came to an agreement with a group of right factions led by so-called 'moderate Labor', headed by former Andrews minister Adem Somyurek.

That new alliance, under the leadership of figures like Stephen Conroy and Kim Carr, is trying to end the 'stability pact'.

In Jagajaga, former state MP and local branch member Brian Tee is understood to be nominating. But insiders say it is difficult for a man to replace a woman in the ALP, given the party is striving for equal representation.

Jane Garrett has been named as someone who could nominate for Jagajaga. ( AAP: Angus Livingston )

Former state MP Jane Garrett, who is a senior figure in the new industrial left, has also been suggested and could receive support from Mr Somyurek's group, which has strong local numbers. Ms Garrett could not be contacted for comment.

It's not just Labor contemplating generational change in the lead-up to the next federal election.

Liberal National Party members have voted to dump senators Ian Macdonald and Barry O'Sullivan from the top spots on the party's Queensland Senate ticket.

At a pre-selection meeting in Brisbane, members voted to replace Senator Macdonald with Paul Scarr and Senator O'Sullivan with Susan McDonald.