One of the country's leading constitutional lawyers says Enda Kenny will be required to formally resign as Taoiseach if he fails to win majority support in the Dáil this week.
The former Attorney General John Rodgers says there was a precedent in 1989 when the then Taoiseach Charles Haughey was forced to resign, but stayed on as caretaker Taoiseach until a Government was formed.
The lower house will vote on the issue on Thursday with Mr Kenny, Micheál Martin and Gerry Adams all expected to be put forward.
Mr Rodgers said article 28 of the Constitution was very clear and he believes this would apply if the same happened this week.
He said: "Mr Haughey did resign, so far as I remember it, and that resolved the issue and I think that is the appropriate way it should be resolved.
"My view is that it is a very important signal that the Constitution is effective, that that would happen.
"And I think that's what should happen, if Enda Kenny doesn't secure the support of the majority of Dáil Eireann."