It's becoming a game of political cat and mouse between National and Labour over whether the Red Peak flag design is included in the first referendum on which is the favourite design.

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National said if Labour agreed to support the referendum process then the new design could be included in the final four.

Labour's Andrew Little said he'd support the Red Peak option providing the Government allows a yes or no vote on flag change in the first referendum which runs from November 20 to December 11.

"It may well be that the presence of Red Peak on the ballot paper for a second referendum question that asks them to choose between whichever flag may well cause enough people in the first referendum to say yes we want to change the flag."

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Little said the party's concern is around the referendum's costly process.

"Our concern has always been about the cost of the referendum and the growing likelihood that we could get to the end of the second referendum having spent the rest of the $26 million and we end up with the same flag."

Tens of thousands of people have supported Red Peak on social media, with more than 46,000 signing an online petition calling for the inclusion of the design in the referendum.