The West Australian quit shadow cabinet on Friday saying he wanted to be able to speak more freely about immigration issues, given rules on cabinet solidarity.
Liberal senator James Paterson said Mr Hastie's departure from the shadow cabinet was unfortunate but understandable.
"He's done the right thing and the honourable thing, because he could not agree with the approach under (Opposition Leader) Sussan Ley," he told ABC radio on Monday.
"When you respect the Westminster conventions, as Andrew does, as I do, then the only responsible thing to do is to step down from the frontbench."
Senator Paterson insisted Mr Hastie's decision was not a signal that Ms Ley could face a leadership challenge.
There wasn't going to be a spill against Ms Ley in this term of government, he added.
"This isn't about the leadership, this is about his fundamental convictions on issues of policy and his desire to pursue those from the backbench," he said.
"We have just come off at the worst loss in the 80 years of the history of the Liberal Party and, necessarily, we're going through a period of introspection and debate, and part of that has to be public."
A decision on who will take over Mr Hastie's shadow portfolio of home affairs will be made in the coming days.
Mr Hastie's exit coincides with a Newspoll revealing that the coalition's primary vote remains low at 28 per cent compared to Labor's 37 per cent, which is the government's best result since mid-2023.
The slump for the coalition happened alongside a gain in primary support for the far-right party, One Nation, which rose to to 11 per cent - its best outcome since 2017.
On a two-party basis, the government is leading the coalition by 57 per cent to 43 per cent.
Deputy Liberal leader Ted O'Brien admitted that the party looked "messy" after Mr Hastie's resignation, but that was part of the process after its May election loss.
"This is democracy at work ... but this is the way you get good policy, and we're not shy of going into bat and debating policy, and that's really what you're seeing here," he told Nine's Today program.
Asked about the coalition's prospects since its election drubbing, Nationals MP Barnaby Joyce said MPs had to "accept the blame and spread the pain".
"One Nation is going up - that tells you something about what the views of the people are with regard policy structure," he told Seven's Sunrise program.
Asked why some conservative voters appeared to be abandoning the coalition for One Nation, Mr Joyce said it was part of a global phenomenon.
"This is what you are seeing around the world with Nigel Farage in England, Marine Le Pen in France ... the Republicans," he added,
"But the Labor Party shouldn't get too carried away."
