Former minister for finance Paschal Donohoe has said he never had the desire to be taoiseach.
Mr Donohoe announced yesterday that he was resigning from his role in the Government to take up a position at the World Bank.
He also confirmed that he will stand down as a TD for Dublin Central later this week.
Speaking on RTÉ's Today with David McCullagh, Mr Donohoe said: "The pinnacle of my ambition was to be the minister for finance."
He said the only reason he is leaving politics is because his new job presented a "once in a lifetime opportunity", adding that "you need to take these opportunities when they come along".
Mr Donohoe will take up the second most senior position in the World Bank, as its Managing Director and Chief Knowledge Officer.
He said the role is responsible for all of the economic policies of the World Bank.
"These include the kind of policies that help make the world a better place and include supporting vulnerable communities all over the world deal with the effects of climate change," he said.
He added that had this opportunity not presented itself, he would have been very happy to continue in his political role.
He said that everything about his new job took shape over the last few weeks, adding that there was a process that led up to that point.
Mr Donohoe said he considered not contesting the last general election but decided to stand because he had always said he would stand in election 2024.
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He added: "The scale of departure of our party and Leo Varadkar's decision to step aside cemented my decision to stand.
"Everybody has a plan, but when the context around that plan completely changes, you then assess what you're going to do. And really it was my commitment to Simon [Harris], actually, and my faith in him, and my determination to make the case for a particular type of politics."
Mr Donohoe said he believed the centre of politics will continue to hold and grow.
He said he was delighted that Mr Harris is the new Minister for finance, adding that the Tánaiste is very familiar with the demands of the job and he also shares his views on the economy.
"He was the minister of state in the Department of Finance and then critically, he was Taoiseach and Tánaiste and worked with me on two budgets," Mr Donohoe said.
He said that he and Mr Harris had been in full agreement on the last budget and denied that they had opposing views on VAT.
"Our outlooks are identical and that is one of the reasons I have a certain sense of closure," he added.
Fine Gael will win by-election for seat
Mr Donohoe also said he believes Fine Gael will win the by-election for his seat.
He thanked the people of Dublin Central and said he would be forever grateful for the courtesy and support they have given him for over 20 years.
When asked about the possibility that Gerard Hutch might contest the by-election, Mr Donohoe said that it is up to anyone to decide if they want to contest it.
"The people of Dublin Central will decide who they elect," he said.
