He contested the seat in 2014 and received 8630 votes, polling third behind National's Alastair Scott on 16223 and Labour's Kieran McAnulty on 9452.
Mr Mark, who was a New Zealand First list MP from 1996 until the party was ousted in 2008, returned to parliament in last year's election.
Mr Mark said it was proving difficult to find an office location that was both appropriate and affordable.
"We are still looking, we've visited a number of premises but there's a limited budget and we have to work within that."
List MPs had smaller budgets and it was a matter of finding premises that fit within that, he said.
"We've had the sign-off from all the required levels -- but having not been the MP for Wairarapa there's a smaller budget available."
Premises in both Carterton and Masterton had been viewed, but Masterton appeared the most likely option at this stage, Mr Mark said.
"It's clear that it probably needs to be in Masterton so that's our first preference now, and we are doing our very best."
Although his responsibilities had increased since being elected as deputy leader, Mr Mark said he tries to spend Mondays, Fridays and one weekend day in Wairarapa.
Once a suitable premises has been found and given final approval by parliamentary security, the Wairarapa office, which will be manned by two local staff members, will be open Monday to Friday from 9am to 3pm.