Mr Crosby said it wouldn't be possible to do both jobs, but Mr Mitchell is adamant he could manage it.
Mr Mitchell spoke to media about his plans after his candidacy was ratified.
He explained how he planned to manage to do both jobs, and how he was 100 per cent committed to his role as a councillor and also his potential role as an MP.
Until he is in that position and gives it a go, I doubt it could be achieved successfully.
Being a city councillor is a demanding role. As is being an MP. Realistically, how can you divide your time between both jobs?
As an MP, you would be expected to spend a decent portion of your time in Wellington, meaning you would miss out on various local events and city council meetings. You simply cannot be in two places at once.
The issues you would be dealing with at a local body level would be different to those you would have to deal with in Parliament. Could you put enough effort into both?
Would you always be able to put your constituents first?
Mr Mitchell said it would be beneficial to the city council to have an elected member also in Parliament and that he had the support of his fellow councillors as well as the council chief executive.
However, people I have spoken to are unsure of the logistics of how it would work.
I don't doubt Mr Mitchell's ability to multitask, but the issue is the demanding work he is embarking on.
To quell rumours of double dipping, Mr Mitchell said he would be paying back a percentage of his council salary, a percentage that has not yet been determined.
Earlier this week National Party Napier candidate Wayne Walford announced he was stepping down from the role of Hawke's Bay Chamber of Commerce chief executive.
Mr Walford, who was named four months ago as National's candidate, had originally intended taking leave from the chamber role from August 8, but will now make the break from next Monday.
He said it had become "more and more difficult" to carry out the two roles and maintain the integrity of the chamber role while conducting the National campaign.
But the move came too late for chamber member Murray Painter, who wrote online: "I feel that to pay a membership that helps fund someone who is continuously in the press speaking from a political party perspective, rather than advocating for business as the head of a business group, is wrong."
I know there are some major differences between Mr Mitchell and Mr Walford but the principle is the same.
You are already in a demanding role. You are being paid to represent people and you are their voice when it comes to concerns and changes within the community. You were voted in to do that role, and now you are deciding to split your time with another demanding position.
I think Mr Mitchell has the best of intentions but the people who voted him in may not agree. His good intentions may not be achievable.
To become a city councillor he campaigned on putting the Mount and Papamoa first. He wanted to help people living in those areas.
Is he still putting those people first if he gets voted into Parliament?
Time will only tell.