Light rail and housing have shaped up as the main issues in RNZ's live debate with Mt Albert by-election candidates Jacinda Ardern, Geoff Simmons and Julie-Ann Genter.

Look back at the debate here:

Labour's Ms Adern, Mr Simmons of the newly formed Opportunities Party and Ms Genter of the Green Party are among 13 candidates competing for the seat in this weekend's by-election.

National has chosen not to stand in the safe Labour seat.

Labour's Ms Ardern said the median age of people in Mt Albert was 33, and 40 percent were renting. She said the average house size in central Auckland 200 sq/m, which was not affordable and only 5 percent of new builds were affordable.

She said for large building programmes, such as those of Housing New Zealand, it was essential to have general planning overall to ensure there was transport planning and school planning, an area which was currently very squeezed in Mt Albert.

Ms Genter said National was looking particularly at foreign investment, which would not solve New Zealand's housing problem and would not build the city wanted for the long term.

She said high end developers in Auckland seemed to be aiming at the high end of the market which was not good in the long term.

Mr Simmons said the party was proposing a tax on all assets which would give a strong incentive to intensify building in the central city.

He said the party would get rid of tax incentives to landbank.

Mr Simmons said the party also favoured a congestion charge, which would take away the incentive to have urban sprawl.

Transport

All candidates supported light rail for the area, and a contribution from government funding.

Mr Simmons said the Transport Agency should contribute to all modes of transport, including a 50-50 split with Auckland Council investment in light rail.

A congestion charge was also required. "The government has agreed that a congestion charge is on the cards but we need to start working on it now to get in in the next four or five years."

Ms Adern said light rail must be a stepping stone towards rail to the airport. "That has to be an absolute priority." The government should support Auckland Council in providing in light rail from the city down Dominion Road.

Ms Genter said a congestion charge was not the best policy - it was "a way to raise revenue to pay for more highways".

Better public transport would allow people to move more easily around the city and said government funding should be at least 50 percent of transport infrastructure. There was also the opportunity to give local councils the ability to raise revenue for infrastructure rather than relying solely on rates.