And all three main candidates have either low places on the party list, or have withdrawn from the list altogether, meaning they all need the seat to ensure passage to Parliament.
New Zealand First has not won a seat since 2002. An electoral seat would be treasured by the party, as well as for Mr Mark, who is being touted as an eventual successor to leader Winston Peters.
Mr Mark is eager to promote his experience of 12 years as an MP, as well as the local connection as the Carterton Mayor.
National's Alistair Scott -- enrolled in Wellington Central but with a second home in the electorate -- has a headstart, given the National Party commanded a majority in 2011.
But Labour's Kieran McAnulty, who boasts five generations in the region, fancies his chances now that Mr Mark has entered the fray. In 2002, the right vote was split between three parties, handing victory to then-Labour candidate Georgina Beyer.
"And when Ron Mark stood in Rimutaka in 2008, he made a lot of noise about winning the seat and ended up splitting the National vote, and [Labour's] Chris Hipkins won," Mr McAnulty says.
Mr Scott is dismissive of New Zealand First. "Electorate votes on Ron are wasted because he's not going to win or even come second."
Agriculture and forestry feature heavily in the mostly rural region, where about a quarter of residents earn less than $35,000 a year. Regional development is an obvious focus.
Mr Scott, who owns a vineyard near Masterton, supports the Wairarapa Water Use and Ruataniwha irrigation projects to boost farming.
"I support a regional economy, and not a [Labour/Green] capital gains tax and a [Green Party] carbon tax which will hurt the region ... and incentivise everyone to sell their assets and go and buy a big house in Auckland."
Mr McAnulty trumpets Labour's $200 million regional development fund, and its plan to boost the minimum wage by $2 an hour next year.
He is against a region-wide referendum into a Wellington Super City Council, which could include the southern parts of the electorate, and wants each district to be able to decide its own fate.
Mr Mark is more unequivocal about a super city. "That's not what 85 per cent of the people want. I can best fight that from Parliament. I have a good relationship with both major parties."
He says the Government's roading plans take a "metro-centric" view and neglect the exports-focused region. "That means some roads will have to be gravel, or we will have to pass costs to ratepayers. For Carterton alone that could mean a 3 to 4 per cent increase in rates."
He and Mr McAnulty both take issue with Mr Scott's local credentials, which Mr Scott shrugs off: "It's not about where you were born. It's about your commitment and your experience."
Wairarapa
- Held by retiring MP John Hayes, National, majority 7135.
- Large, rural seat that includes Featherston, Greytown and Masterton and the southern Hawkes Bay towns of Woodville, Pahiatua and Dannevirke.
- About 25% of people earn less than $35,000 a year.
- About 20% work in agriculture, forestry and fishing, more than three times the national average.
- 2011 party vote: National 51.5%, Labour 23%, Greens 9.8%, NZ First 7.8%, Conservative 3.75%.
