A bill to decriminalise abortion is before the NSW Parliament, with the issue sparking tensions within the coalition government.

Mr Morrison, who is a Pentecostal Christian, said it was a matter of conscience for state MPs ahead of a delayed vote in the upper house next month.

"It's not a matter before the commonwealth parliament nor is it one I'm seeking to have brought before the commonwealth parliament," he told The Sydney Morning Herald on Wednesday.

"I have what I would describe as conservative views on this issue as people know I have on other issues. That's really all I think I need to say."

Former deputy prime minister leader Barnaby Joyce directly lobbied the prime minister and federal Nationals leader Michael McCormack to speak out against the abortion bill.

Mr Joyce also threatened to quit the Nationals after being criticised by his party for leading an anti-abortion rally in Sydney.

But Mr Morrison has declined to enter the fray and Mr McCormack also said the abortion legislation was a matter for the NSW parliament.

Australian Associated Press