Mr Cunliffe said the offer was being made in good faith.
"I know we're exposing ourselves to some risk on this but the issue's important and we're willing to work with the Government on this."
Mr Cunliffe said Labour hadn't previously said it would support parts of the bill because "they haven't provided a draft text".
With the Maori Party and United Future saying they wouldn't support a bill that changed the Act's principles, "The Government may now wish to separate the bill into two bills and seek broad bi partisan support for the housing affordability measures."
But speaking earlier to reporters, Environment Minister Amy Adams was cold on the idea of splitting the bill so that the Government's support partners could "vote for the bits they like and not the bits they don't".
"It's the usual thing. If you want different outcomes then you've got to be prepared to do things differently and we know that at the moment we're not getting enough land made available for housing, we're not getting enough new jobs and new businesses being created in some of our regions and know a big part of that often is down to the way the RMA works so in our view if you really want to make a difference in those things you've got to be prepared to acknowledge that the RMA is there to both protect our environment and provide for all the needs of our communities."
Ms Adams said the Government could have watered down the RMA bill "and not made them do very much".
But "at the end of the day we knew the RMA needed substantial reform if it was make a difference and we stand by that so we'll take it to the election."
Meanwhile, Ms Adams refused to comment on news South Island iwi Ngai Tahu had pulled its support for the massive Ruataniwha irrigation project in Central Hawke's Bay.
Last week Ms Adams and Conservation Minister Nick Smith gave the board of inquiry which will decide on the future of the project a time extension to reach their final decision.
The board of inquiry has given initial approval but introduced wide-reaching environmental conditions for the affected catchment which project supporters say will affect its viability.