The former environment minister also says he was “shafted” on going for the Labour leadership and is “annoyed” at party leader Brendan Howlin preventing a contest.

His interview with Hot Presswill likely ignite debate about the future of Labour after its bruising election results last year and continued low polling.

Asked about Labour reaching out to the left, Mr Kelly said: “I would like to see the Social Democrats, in particular, and the Labour Party coming together.”

“There should be a natural coming together. They have many fine members. It’s hard to distinguish between Social Democrats and Labour. And there’s others: there’s Independents and people across other parties. And really for the future of social democrats — which we all are — and the future of democratic socialists, really, there needs to be that coming together to forge a block not just in Leinster House but across the country.”

The Tipperary TD said he was “shafted” when it came to being prevented from competing to succeed Joan Burton as Labour leader last year. “Yes. I was pretty annoyed about what happened. It was a difficult period but I’ve moved on.”

Mr Kelly said it was wrong there was no grassroots vote and a decision was made by three party deputies as opposed to thousands of members.