Fine Gael leader Enda Kenny has said he 'fully expects' to win tomorrow's vote of confidence in his leadership.
Mr Kenny's is remaining confident despite the party's Justice Spokesman Charlie Flanagan indicating that he will vote against the current leader in tomorrow's confidence vote.
It is understood Deputy Flanagan informed Mr Kenny of his decision this afternoon.
Deputy Flanagan also expressed hope that the party could move forward in a united way after tomorrow's meeting.
He is the eleventh member of the 19-member frontbench nominated by Mr Kenny who has publicly said he has lost confidence in the leadership.
Simon Coveney, Denis Naughten, Olwyn Enright, Olivia Mitchell, Fergus O'Dowd, Michael Creed, Billy Timmins, Leo Varadkar, Brian Hayes and Richard Bruton have all said they no longer have confidence in Mr Kenny's leadership.
Sources in Richard Bruton's camp said Mr Flanagan's decision marked a decisive shift in the situation.
Earlier, the party leader suffered a blow with the man he appointed acting Finance Spokesman on Monday, Kieran O'Donnell, opting for Mr Bruton.
Dublin TD Lucinda Creighton, who is backing Mr Bruton, says she and a number of others have been promised a front bench job if they publicly declare for Mr Kenny.
Elsewhere, Paschal Donohoe came out in favour of Richard Bruton, while Senators Maurice Cummins and Paul Coghlan declared for Mr Kenny.
Former party leader Michael Noonan has refused to say who he will be backing in his party's leadership race.
Speaking outside Leinster House, Mr Noonan said he knows which candidate will get his vote but said it would be inappropriate to divulge that publicly.
He said he had sympathy for both Mr Kenny and Mr Bruton but said he was not surprised by the move as there had been rumblings for some time.
Mr Kenny offered something of an olive branch in an interview on RTÉ's Six One News yesterday, suggesting that he might find places for his opponents in a new-look frontbench to be unveiled next week.
However, his opponents were unimpressed with some claiming that many party members had been promised promotion if they backed the leadership in the confidence vote.
Bruton vows to be 'unifying force'
Mr Bruton has said he will be a unifying force should he win.
He said he would accept the democratic will of the party in terms of the leadership, but - should he lose - he would not accept a re-appointment to the frontbench.
He said to do so would be hypocritical, given his lack of confidence in Mr Kenny.
He said he worked with Mr Kenny for as long as he could, but had to listen to what the people were saying about his leadership.
Whoever wins the leadership contest, personal relationships within the party are likely to be severely strained by this challenge to Mr Kenny.
Hogan calls on rebels to rejoin
Fine Gael frontbencher and Enda Kenny supporter Phil Hogan has called on Richard Bruton and his supporters to rejoin the party team after tomorrow’s vote, which he predicted Mr Kenny would win.
Speaking at Leinster House surrounded by a large group of Kenny supporters, Mr Hogan asked Mr Bruton to consider the implications of his refusal to serve on the front bench should he be defeated tomorrow.
He said Enda Kenny had won more votes and more seats in each election in which he had led the party and called on TDs and Senators to honour the party pledge of loyalty which they had signed.
Earlier, Mr Bruton told journalists he had the track record to ensure that Fine Gael achieved its potential under his leadership.