Indigenous Affairs Minister Nigel Scullion, 62, on Saturday became the latest to announce he will be standing down, believing it's simply time for him to go after being in parliament since 2001.

That came after Perth-based Human Services Minister Michael Keenan revealed on Friday evening he wouldn't be running again, in order to spend more time with his wife and four children aged between six months and seven.

Opposition Leader Bill Shorten says the retirement announcements shows the "government was barely limping to the end of its term."

"This is a government where its members have given up and now they're walking out the door," he told reporters in Melbourne.

But Mr Morrison said their reasons should be taken at face value, dismissing suggestions they could be inspired by perceptions the government is 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 to the decisions that they've made," the prime minister told reporters in Canberra on Saturday.

"Both of these cases - because this is how it has been shared with me by both of these men - are about their own personal circumstances.

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

Industrial Affairs Minister Kelly O'Dwyer also announced her retirement plans for family reasons last week.

When asked whether the frontbenchers bowing out could hit the government's re-election chances, Mr Morrison simply said "no".

"What I'll be equally pleased to see is those that'll come up and refresh behind them. All government's refresh," he said.

Senator Scullion was not as confident when the same question was put to him, saying he didn't know what impact the retirements would have.

But he and Mr Keenan said they were sure of the coalition's ultimate success at the election, likely to be held in May.

"I'm very confident they will win," Senator Scullion told reporters in Darwin.

The prime minister said there were no more resignations before him.

He also sought to hose down reports he had been lobbying NSW MP Craig Laundy to stay in the fold, saying he caught up with him this week after arranging to do so while he was overseas over the break.

"I said let's catch up for brekkie when you get back and that's what we did," Mr Morrison said.

Senator Scullion, Mr Keenan and Ms O'Dwyer will remain in their ministerial portfolios until the election.

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RECENT GOVERNMENT RESIGNATIONS:

- Indigenous Affairs Minister Nigel Scullion

- Human Services Minister Michael Keenan - personal reasons

- Jobs Minister Kelly O'Dwyer - personal reasons

- Nationals MP and former assistant minister Andrew Broad - fell from grace in the sugar daddy scandal

- MP Julia Banks - cites bullying

Australian Associated Press