CORK North Central TD Billy Kelleher and former County Mayor Seamus McGrath will both be contesting the selection convention to replace Brian Crowley on the next Fianna Fáil ticket in Ireland South.
Both men paid tribute to Mr Crowley upon his retirement.
"He was one of the biggest names in Irish politics," said Mr Kelleher. "His record speaks for itself. That has been acknowledged with the consistent support he received from all areas of life and all areas of the constituency," he added.
"It’s very important to recognise his enormous contribution over almost three decades of public service," said Mr McGrath.
"It is clear that he has had a very difficult time with his health problems and we can only imagine what he has gone through.
"I want to sincerely wish him all the best for the future and thank him for his service," he added.
Mr Kelleher's candidacy could cause friction in Fianna Fáil as party leader Micheál Martin has said that he does not want TDs running for the European Parliament.
The party wishes to avoid any by-elections that would result if a TD was elected.
However, Mr Kelleher said that he does not believe that he will be blocked from running.
"I don't think that will be the case. At the end of the day, it will be the members that have the choice," he said.
The former Junior Minister said that he has the skills and experience from his time in national politics to serve Ireland in Europe.
"I'll be explaining why I would I believe I would be a good candidate for Fianna Fáil, and if members select me, why I would be a good MEP," he said.
Mr McGrath said he can provide a fresh option to voters in at an election that is "critically important" for Ireland.
"There are key challenges ahead across a range of issues and I have the energy and enthusiasm to get stuck in.
"I genuinely believe there is an appetite among the electorate for new faces and fresh ideas.
"This is an exciting journey for me and with the support of my family and party colleagues, I very much look forward to the coming weeks,“ he said.