(Reuters) - New Zealand s two main parties are neck and neck in opinion polls after the appointment of a charismatic leader boosted the opposition Labour Party, threatening the governing National Party s decade-long hold on power. The election is on Sept 23. Below are the main parties  positions on key issues: ECONOMYNew Zealand s once booming economy is facing some capacity constraints. Unemployment is at an eight-year low and a labor shortage, most noticeably in construction, threatens to curb growth. Both main parties plan to be fiscally prudent and maintain a budget surplus, but would differ on monetary policy. National plans to cut net debt to 10-15 percent of GDP by 2025, while Labour and the Green Party both plan to cut it to 20 percent of GDP within five years of taking office. Labour proposes adding full employment to the existing inflation mandate of the Reserve Bank of New Zealand, which economists say could lead to easier monetary policy and fuel longer-term inflation. To form a government, National may be more dependent on New Zealand First, which favors greater currency intervention - something New Zealand has been reluctant to do in the past. National is planning to adjust tax thresholds, or effectively deliver tax cuts, from April 2018 to boost family income. Labour wants to do away with National s planned tax cuts and boost tax credits and subsidies. New Zealand s house prices have risen more than 50 percent in the past decade as the construction industry failed to keep up with demand from a growing population, fueled by record migration and an increasing number of New Zealanders staying home. Labour criticizes National for leaving the housing crisis unresolved after nine years in government. It wants to ban overseas buyers from purchasing existing homes and build 100,000 affordable homes over 10 years. It also plans to create a housing authority to speed up residential development. National questions Labour s ability to build so many houses while curbing immigration. It plans to make NZ$1 billion available to speed up the development of 60,000 houses. New Zealand First wants to ban foreign non-residents from owning a home in New Zealand, except in particular cases, and to  provide government assistance for first-home buyers. The Green Party wants to provide 10,000 new houses over 10 years for low-income groups through a rent-to-buy scheme. The National Party tightened eligibility criteria this year for immigration and believes current levels of immigration are about right to meet the economy s needs. Labour plans to reduce net immigration by up to 30,000 from record levels of over 70,000 annually and to charge every visitor a NZ$25 fee, which would be ring-fenced for a NZ$75 million infrastructure fund. The Greens want to review immigration policy to make sure migrants match the skills employers need, in line with Labour s policy. New Zealand First wants to curb immigration by ensuring New Zealand workers have the first chance at jobs and by capping the number of older migrants. National wants to expand New Zealand s international trade. Among other plans, it wants to complete the Trans-Pacific Partnership trade deal, launch a free trade deal with the European Union and Britain post-Brexit and upgrade its free trade agreement with China. Labour wants to reconsider New Zealand s role in the Trans-Pacific Partnership trade pact if provisions on foreign investment are not changed to allow the New Zealand government to restrict investment into the country. New Zealand First wants to renegotiate the TPP. 
Factbox: New Zealand 2017 election - main parties and policies