The Labour Party is promising to improve access to healthcare for young people, proposing to extend school-based services to all public secondary schools.

Deputy leader Jacinda Ardern announced the policy at the party's congress in Wellington today, in which Labour marked some of its policy planning to contest this year's general election in September.

Labour's policy would see every state secondary school get a nurse with call-in support from a GP at an estimated cost of $40 million a year, funded from the health budget.The school-based health services were introduced under the Labour government in 2008 and currently funds nurses in decile 1-3 schools.

Ardern drew attention to young peoples' mental health in her speech.

"Behind every single entry in the suicide statistics lies not only a life lost but a community shattered," she said.

"We can repeat the statistics over and over, but it is the names and stories that almost all of us will know that bring home the effect of this disease in our country."

"Everyone student who needs it will have the option of having someone they can go to, someone they can trust," she told the party faithful. "A young person's wellbeing, no matter where they live, what community they are in, will be our priority."

Ardern also highlighted the problem of youth disengagement from electoral politics, and admitted worrying that young peoples' apathy was becoming more widespread.

Earlier in the day, Labour's finance spokesperson Grant Robertson promised to bring the unemployment rate - which is currently around five percent - down to four percent.

Robertson also signalled the party was looking to change tax laws on housing separately from a wider review it's planning of the tax system, pledging to address negative gearing, a set up that allows property investors to claim tax breaks on their property portfolios.

Labour are also looking to invest heavily in road and rail infrastructure, but Robertson told media he wouldn't be giving out specific costings just yet.

"We'll come up with a firm number on that once we've seen the government's numbers in the budget," he said. "The point that I was making today was that in addition to using the government balance sheet to borrow to be able to fund that, we're also looking at infrastructure bonds, particularly for Auckland."

Robertson was forced to clarify that he wasn't talking about New Zealand First leader Winston Peters when he insisted that any debate about immigration should always be a debate about policy, and anyone who makes immigration about race must be called out.

"Genuinely, it's not about any individual person," he claimed to reporters. "I wanted to make a statement today about Labour's values on immigration, about the process we're going through to get policy that is better responsive to the population growth that we've had."

"That was all I was trying to do."

Meanwhile, outgoing long-term MP and and former deputy-leader Annette King paid tribute and thanks to the party.

King is set to depart parliament at this year's election, signalling her intention earlier this year to step down after 33 years as an MP, and 44 as a Labour Party member.

"I would not be standing here if the Labour Party hadn't given me the opportunity to be a member, and then the opportunity to serve in most roles of the party including the national executive, and finally to become a member of parliament in the wonderful seat of Horowhenua," King said.

Party leader Andrew Little is due to appear at the party congress tomorrow.