A third federal minister has announced his resignation from politics, with Indigenous Affairs Minister Nigel Scullion saying he will not contest the next election.

Key points: NT senator Nigel Scullion will end a 17-year political career at the next federal election

NT senator Nigel Scullion will end a 17-year political career at the next federal election The outgoing Indigenous Affairs Minister's key policies and programs had mixed results

The outgoing Indigenous Affairs Minister's key policies and programs had mixed results He had colourful and controversial moments in the spotlight

In a blow to the Government's re-election hopes, Senator Scullion joins Human Services Minister Michael Keenan and Jobs Minister Kelly O'Dwyer, who both announced this week they would step aside from politics to focus on their families.

Senator Scullion made his announcement on Australia Day, calling time on nearly two decades in federal politics.

"It has been the greatest honour of my life to serve the people of the Northern Territory for the last 17 years in the Australian Senate; I thank all Territorians for their support over this time," he said.

Prime Minister Scott Morrison rejected suggestions the three ministers were abandoning a sinking ship.

"I don't think that's a very kind way to put it, and I don't think that really does respect the decisions they made," he said.

He also denied it would hurt the Coalition's chances of winning the next election, saying the resignations were about nothing more than the "personal circumstances" of each politician.

"We've had members retiring and not standing at the next election from both sides of politics, and it means nothing more than that," he said.

"All governments refresh and that's a process that's going on."

Nigel Scullion had a long and at times controversial political career. ( AAP Image/Alan Porritt )

The Prime Minister refused to guarantee no other ministers would resign before the election, saying Opposition Leader Bill Shorten would not be able to make the same commitment.

However, he tried to pour cold water on reports he was convincing former minister and Malcolm Turnbull supporter Craig Laundy to recontest his marginal Sydney seat of Reid.

"I caught up with him for an hour during the week, he was overseas when I was calling many members over the break, as you'd expect me to do as their leader, and I said 'let's catch up for brekky when you get back' and that's what we did," he said.

"At present he's continuing forward."

Mr Shorten seized on the issue, saying the Government's own ministers had "given up".

"This just shows a Government that's barely limping to the end of its term," he said.

"I suspect if the rumour mill is right, there's plenty more to come.

"The Government has had nine of its current ministers and backbenchers say 'that's it'. They're either not recontesting or their party has dumped them."

Greens leader Richard Di Natale declared there would be more resignations ahead of the poll.

"What we're seeing are ministers abandoning a government that has almost no chance of winning the next election," he said.

"With the Government almost certain to be turfed out, we are seeing now ministers and backbenchers express no confidence in Scott Morrison's ability to win government for the Coalition, and they're jumping ship.

"Nothing is going to be able to redeem this government."

'People hyperventilate about everything in politics': Keenan

At a press conference in Perth, Mr Keenan also rejected claims he was resigning to avoid embarrassment at the election.

"It's actually not that unusual that people make a decision at this time of year not to recontest, and you'll see there's actually members on the other side of politics that are leaving," Mr Keenan said.

"This is a job where you've got to give 110 per cent, if you're not prepared or you don't think you can provide that for the next three years, then I think you've got an obligation not to stand, and allow somebody else who still has all that vim and vigour and hasn't got other priorities to go ahead and represent the people."

It is understood Mr Keenan wants to spend more time with his young family. ( ABC News: Madeline Palmer )

He said "people hyperventilate about everything in politics" and did not believe it was "particularly striking" that several ministers announced their resignations after Christmas, with an election looming.

Mr Keenan holds his electorate of Stirling by a margin of 6.1 per cent, and said the chances of the Liberal Party holding onto the seat were "exceptionally good", despite his resignation.

"I faced some very tough elections as a member, including winning this seat from the Labor Party … we've got a big war chest and great amount of community support," Mr Keenan said.

"I'm very, very confident we'll retain this seat."