In a light hearted dig at Dr Whyte, Mr Parker said "we've promised Epsom that if we're elected and they elect Act we'd like an RMA-free zone for Epsom and see how long it is before they want the RMA back".
"A few more prisons, nice five-storey buildings blocking everyone's view, all permitted without the RMA", he said, drawing laughter from the audience.
Earlier, Mr English said his Government wanted to reform the RMA to shorten the process and reduce costs for applicants to make it less discouraging to investment while preserving the right of communities to be heard.
But despite having "80 per cent agreement" from parties across the political spectrum the bill wasn't passed before Parliament rose for the election due to the loss of Act's vote.
The bill was still "sitting there" and would be revisited if National won a third term.
Tax was the other big issue at this morning's conference with Dr Whyte saying beyond his party's goal to reduce the corporate rate from 28 per cent to 20 per cent, which he said would boost economic growth, Act wanted to drop the rate ultimately to 12.5 per cent.
Mr English said paying down debt was a higher priority for National than corporate tax rate cuts.
Mr Parker said Labour planned to reduce the tax burden on businesses but through mechanisms such as research and development tax breaks rather than through a corporate rate cut.