Foster has announced a plan to build more than 90 homes on a sports field in Happy Valley.
He said he also wanted to change planning rules and look at where housing could be intensified and push for an urban development agency.
Foster announced his bid for the top job alongside Sir Peter Jackson, who is bankrolling some of his campaign.
Both have been vocal critics of a proposed development at Shelly Bay.
Foster rejected any suggestion Jackson was "pulling his strings".
The reason he had not already disclosed how much money Jackson was giving him was because he hadn't been able to get hold of the film-maker, he said.
Foster said Jackson supported him because of his track record opposing the development and confirmed he had several other "significant" donors.
He said he would not vote on future Shelly Bay decisions if Jackson had a pecuniary interest.
Lester is running for a second term on the Labour ticket.
He said his campaign was voluntary and anyone from Labour HQ was helping in their private time.
"Labour doesn't contribute to the campaign but I've got 250 volunteers that get out there and help me."
On transport, Lester said the city had been waiting for 40 years for serious investment in its transport infrastructure.
He said he wanted to get on with the government-endorsed $6.4b Let's Get Wellington Moving project.
"I've done absolutely everything I can to get the best deal for Wellington."
He said the council would look at paying its share with a car park levy, value capture and a targeted rate increase of 1.2% for 12 years.
But Foster warned that increase was cumulative.
He doubted the business case for mass rapid transit, the project's golden child, would stack up.
He said he would rather get on with bus priority, improvements at the Basin Reserve and a second Mt Victoria Tunnel.
It wouldn't be a Wellington mayoral debate without mentioning Julie Anne Genter's secret letter.
Speculation is rife the letter penned by the Associate Transport Minister and Green MP was responsible for putting a second Mt Victoria Tunnel on the back burner.
"The impression you've got is that it's something she doesn't want to release because otherwise she would have released it", Foster said.
Lester said his understanding was the letter didn't say much.
Foster said Lester presented LGWM as a "take it or leave it deal".
He said he and his colleagues were left with the impression the confidence and supply agreement with Labour could have been in jeopardy if the Greens hadn't got their way.
Lester denied he gave councillors that impression and Genter has previously said the agreement was never put in jeopardy and she never threatened to resign
The debate was livestreamed at nzherald.co.nz and newstalkzb.co.nz and broadcast live on Newstalk ZB Wellington and iHeartRadio.
Heather du Plessis-Allan, Newstalk ZB's Drive host and Herald on Sunday columnist, hosted the half-hour long election special.
