"They have to be careful that we don't move too far from processes that have kept this place in good stead in an ethical and moral and principled way," he told Radio NZ's Morning Report.
His colleague Aupito William Sio, a Mormon, had an open mind: "In this day and age, I think there's a strong feeling of people wanting the prayer to be more inclusive, recognising that many of my colleagues do not acknowledge the existence of Jesus Christ."
New Zealand First has opposed changing it in the past, and deputy leader Ron Mark said the caucus would discuss the issue next week - but he wanted to keep references to the Queen.
"I'm a commissioned officer and a royalist by nature, and New Zealand First has always had quite a conservative view on that."
Greens co-leader James Shaw was happy with Mallard's changes, and although senior National MP Amy Adams did not have an issue with the wording, she preferred something "more secular and reflecting New Zealand's diverse and tolerant nature".
"But I would certainly want to keep a reference to the Queen of New Zealand," Adams added.
Mallard has the final say on the matter.
Changing the prayer has been debated before, most recently in 2014, when then-Speaker David Carter proposed wording that kept a reference to the Queen, but dropped "Almighty God", "true religion" and "Jesus Christ".
He eventually declined to change it after National and NZ First MPs objected. The Greens supported change, and Labour did not have a collective view.
In 2007, 63 per cent of MPs voted to keep the prayer unchanged.