Fianna Fáil Senator Terry Leyden, who is quitting politics after nearly 50 years, has said he would have "no worries" about Mary Lou McDonald being Taoiseach.
Mr Leyden has decided not to run for re-election to the Seanad, bringing to an end a long political career where he served as a TD, senator and as a minister of state under former Taoiseach Charles Haughey.
Mr Leyden said he was "bitterly disappointed" by the election result and said Sinn Féin should be allowed to form a minority government with Ms McDonald as Taoiseach.
"I've no worries about Sinn Féin, I've no worries about Mary Lou being Taoiseach. This is a different Sinn Féin than the Gerry Adams Sinn Féin and the Martin Ferris Sinn Féin. They're more bureaucrats than ideological. They are a new breed of politicians and they are young intelligent and bright," he said.
He said he was "personally not against" his party going into coalition with Sinn Féin - but said he would be advised by Mr Martin on the issue, adding it would be a "far more successful administration if Micheál Martin was Taoiseach".
Mr Leyden (74) is the last remaining member of the current Fianna Fáil parliamentary party to serve in a Haughey government.
He said he would now explore careers in writing, public affairs, or consultancy.
His daughter Orla, who ran for Fianna Fáil in the General Election, is to seek a Seanad seat on the Labour panel.
He described the late Mr Haughey as the "cleverest, most imaginative Taoiseach this country ever had".
Despite the scandal that engulfed Mr Haughey and the various challenges to his leadership, Mr Leyden remained loyal throughout the Gubu era of Irish politics.
"He did not authorise phone tapping," he said. "I am not saying he didn't read the scripts, but it wasn't his initiative."
The Roscommon native was first elected to the council in 1974 and was part of the wave of Fianna Fáil TDs elected in 1977 - the last time the party won an overall majority. He was a minister of state in three departments in the 1980s.
Einstein famously said that the definition of insanity was doing the same thing over and over and expecting a different result. And it appears that the Irish people, after decades of doing the same thing, have finally decided to take a risk by doing something very different and voting for Sinn Féin in order, one presumes, to get a different result.