Supporters say it would be “catastrophic” if a referendum to recognise indigenous Australians in the constitution failed, as Tony Abbott and Bill Shorten prepare to meet Aboriginal leaders to agree on a way forward.

About 40 community leaders will meet with the Prime Minister and Opposition Leader in Sydney on Monday to thrash out a form of words for a referendum on Aboriginal recognition in the constitution.

There is cross-party backing for recognition, as well as strong support in opinion polls and from the Aboriginal community itself.

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“The big question is about the question (in a referendum) – that’s what the argument is going to be about,” Mr Abbott’s chief indigenous adviser Warren Mundine told Sky News.

He said it would be a “kick in the gut” if a referendum did not occur.

Aboriginal recognition campaigner Jackie Huggins, a spokeswoman for campaign group Recognise, agreed, saying it would be “catastrophic”.

“We will not have this opportunity for another generation or two in terms of the goodwill that is out there,” she said.

She urged indigenous leaders to leave their egos at home when they attend the summit.

“When the leaders are in the room and realise the seriousness of this … hopefully they will put their egos at bay in order to get our people and the Australian people across the line on this referendum,” she said.

Mr Mundine said it will be a test for the Aboriginal leadership at that meeting.

He said their discussion would go beyond the room and the individuals in it because it was about the wider Australian community.

“I want us, as a show of good faith, that we actually sit in this room and have this serious conversation about where this nation is going to go in the future,” Mr Mundine told Sky News.

Government frontbencher Scott Morrison said this process to a referendum needed to be treated carefully.

“If it goes too far, it has no chance of succeeding, but if it doesn’t go far enough, then what’s the point?” he told Network Ten.

“The idea of recognition, I think is important, just as I believed the apology was important.”

NSW Minister for Aboriginal Affairs, Leslie Williams, said it universally acknowledged among indigenous communities that it is critical to get the wording right.

“We want everybody to say yes to the referendum and to do that we need to make sure the wording is right,” she said.

“This certainly has to be a bi-partisan approach.”