However, Tauranga Mayor Stuart Crosby said Cr Mitchell should resign as a councillor if he became an MP.
"He has assured me he could maintain his council duties, but if he is successful [in becoming an MP], my personal view would be that he should resign," he said. "You have to dedicate yourself to one job or the other, you can't do both.
"Despite Clayton's energy and enthusiasm, it won't work."
Cr Mitchell is the second newly elected councillor to announce national political aspirations. In March, Steve Morris announced his intention to stand for National in the Bay of Plenty electorate. He was unsuccessful and Todd Muller was named the candidate.
Mr Crosby said he was not surprised when Cr Morris decided to run for National.
"Steve has been involved with the National Party for a long time, but with Clayton it was a surprise. I did know he had some connections to the party, but did not think he would be putting his hand up. In saying that, I do respect his decision."
Cr Mitchell was guarded on his decision to seek selection until it had been ratified, but did say it was an "exciting time".
NZ First Mount Maunganui branch chairman Roy Townhill said Cr Mitchell was one of three people who had put their hand up locally for the position. A selection panel, made up of the board chairman, the deputy leader and the party director, had picked him yesterday.
Mr Townhill said Cr Mitchell's candidacy was likely to be ratified overnight and the process was "a formality".
NZ First Leader Winston Peters said the selection process "hadn't been completed" and he would not talk about the Tauranga candidate until the matter had been discussed by the party's board.
Tauranga MP Simon Bridges said it was good to see most of the major parties represented in Tauranga.
Labour Tauranga candidate Rachel Jones said the selection of candidates indicated an "interesting" election race.
Meanwhile, Moana radio host Pat Spellman has announced he will run as the Waiariki candidate for the NZ Independent Coalition in this year's elections.
The 23-year-old will join Brendan Horan, the party leader and current Independent member of Parliament, who will stand in the Bay of Plenty electorate, while former regional council councillor Michael O'Neill will stand in the Tauranga electorate. additional reporting Ruth Keber