He said he also wanted the chance to prove to people he was capable of doing both jobs, saying if the people who voted him in as a councillor were not happy with his performance he would step down.
Mr Mitchell told the Bay of Plenty Times Weekend he planned on giving up his council salary if elected in the September general election.
He said he would also be looking for feedback from those people who voted him into council in the Mount Maunganui-Papamoa ward.
"I'll give it about six months and if they are not happy with how I am performing I will stand down gracefully and there will be a byelection."
A byelection would cost ratepayers about $70,000, the same amount as Mr Mitchell's yearly salary.
Mr Mitchell said he wasn't concerned about Mr Key's opinion that he couldn't do both jobs. "The only opinion I value is that of those who voted me in," he said.
Former deputy mayor and ousted Mount Maunganui-Papamoa ward councillor David Stewart said Mr Mitchell needed to stick to his original commitment to the constituents who voted him in.
He said it was "naive" of Mr Mitchell to think he could successfully do two jobs.
"Being a city councillor is a full-time job and it needs your full focus and commitment."
Mr Stewart said he found it hard when he was maintaining a job as a councillor and also being on the health board.
Current Mount Maunganui-Papamoa ward councillor Steve Morris had intentions of running for the National Party in the Bay of Plenty electorate, but he missed out on selection.
He said he would have stood down from council if he was successful in being elected to Parliament.
"I am currently working between 30 and 50 hours a week at council and there would be no room for me personally to do both."
He said if Mr Mitchell was successful it would be a "great loss" to the Mount Maunganui-Papamoa ward.
Mr Mitchell said if he was voted into Parliament it would be a win-win situation.
"The city is getting a councillor who will work for nothing and who has their best interests at heart in Parliament."Anita Moran