Dublin's Lord Mayor Hazel Chu said she spoke to Green Party leader Eamon Ryan before throwing her hat in the ring to contest the Dublin Bay South by-election.
The election, triggered by the resignation of Fine Gael's Eoghan Murphy, will be held before the winter.
Mayor Chu, who is also chairperson of the Green Party, said Minister Ryan told her to "go for it".
She will go head-to-head with fellow Green Party Councillor Claire Byrne for a place on the ticket.
Fine Gael Councillor James Geoghegan has said he intends to seek a nomination, while Senator Ivana Bacik is set to contest the race for Labour.
There is also speculation that former TD Kate O'Connell may also put her name in the ring.
The move comes just weeks after Councillor Chu attempted to secure a Seanad seat as an Independent candidate.
But she told The Hard Shoulder she actually got a lot of support for her run.
"My executive of the party came out after the discussions, and the various motions put forward, and they were very clear on the fact that I didn't break any rules.
"And be it that I was not endorsed, I was also not going to be reprimanded because there was a lot of people supporting my run.
"At the end of the day, the nominators for my run were members of the parliamentary party.
"The people who supported me within the Green Party - we don't hear about that.
"You hear about the division and the issues, but what you don't hear about was I got a lot of support, I got a lot of texts and a lot of messages.
"And people were on a lot of groups talking about how great it was that we were promoting diversity".
She said she spoke with her party leader before considering running in this by-election.
"I called him the day after we heard the announcement... I called Eamon that day just to have a chat with him on whether he thinks it's a good idea.
"And he just said 'Go for it'.
"In fairness he said there was a selection convention - as there should be - and it's decided within this selection convention".
She said she would like to bring 'a good result home' for her party.
"I was the only one within my party to record a historic 33% vote... a lot of my colleagues were poll-toppers during the 2019 local election.
"But I took home over 4,000 votes - so over 4,000 votes is quite a lot when it comes to any constituency.
"Even with the Green wave having ebbed, I know that I can do well in that constituency insofar I've been working really hard on the group - especially through my current role.
"I think my local group should vote for me because I will bring a good result home".
Asked about divisions in the Greens, she said every party has divisions.
"I think a lot of people think there's lots of divisions and factions: there is not.
"Every party has divisions, I'm not saying that there's none, I'm saying that every party has divisions.
"And if we talk about divisions and unity... if people are talking about it externally and internally as well... my point is wouldn't a photo of me and Eamon canvassing, laughing and chatting dispel a lot of those rumours?"