Micheál Martin will today begin his first major push to become Taoiseach as he begins crucial coalition talks with small parties and Independents.
There is a growing belief within Fianna Fáil that they should try to form "a minority rainbow government" that would include the likes of the Green Party, Social Democrats and members of the Independent Alliance.
"It's an idea that now has potential. Fine Gael seem to be looking for a way out. They want Enda Kenny out but can't do anything about him while he's Taoiseach so some might welcome a turn on the Opposition benches," said a source.
Sources confirmed last night that "tentative and informal" approaches had been made to these groups about the possibility of them supporting Mr Martin for Taoiseach.
Buoyed by the support of his parliamentary party, Mr Martin would then embark on defeating Mr Kenny in the vote for Taoiseach next Thursday.
If he secures greater numbers than Mr Kenny, sources say Mr Martin will claim to have the "mandate" to attempt to form a Fianna Fáil minority government with the support of Fine Gael.
Any such scenario in which Mr Martin defeats Mr Kenny will spell the end of Mr Kenny's Fine Gael leadership.
"Nobody can win the race to 79 seats, but if we could get into the early 60s then we could put a proposition for a minority government forward," added a Fianna Fáil source. "There are risks that would come with that - but it's a real possibility."
Another source said that if Fine Gael did not support this minority Fianna Fáil government it would force another election, which could further erode Fine Gael's numbers. No formal deals with other parties are likely to happen until after March 10.
Mr Martin, meanwhile, maintained there were no red-line issues for creating a new government because no coalition talks with Fine Gael had taken place.
Addressing Fianna Fáil's first parliamentary party meeting since the General Election, he also confirmed that the party was willing to talk to anyone.
It was attended by the party's 25 newly elected TDs.