Six Cabinet Ministers are set to declare for Minister for Social Protection Leo Varadkar in the contest to replace Enda Kenny as leader of Fine Gael.
Minister for Education Richard Bruton a pledged his support to Mr Varadkar in a significant boost to his campaign.
Minister for Public Expenditure Paschal Donohoe, Government chief whip Regina Doherty, Minister for Jobs Mary Mitchell-O'Connor, Minister of State at the Department of Defence Paul Kehoe and Minister for Arts Heather Humphreys are also expected to back the Dublin West TD.
Mr Varadkar also has the support of four other Ministers of State, nine Senators, 15 TDs and one MEP Brian Hayes.
Minister for Housing Simon Coveney has the support of Minister for Health Simon Harris, and four Ministers of State (Marcella Corcoran Kennedy, Damien English, Dara Murphy and David Stanton).
Two TDs Kate O'Connell and Maria Bailey and Senators including current deputy leader James Reilly and MEP Deirdre Clune are also expected to back the Cork South-Central TD.
Mr Coveney is expected to also secure the backing of Minister for Agriculture Michael Creed. Minister for Finance Michael Noonan and Mr Kenny are also expected to privately be supportive of the Minister for Housing.
Five Cabinet members, Mr Kenny, Mr Noonan, Mr Creed, Tánaiste Frances Fitzgerald and Minister for Foreign Affairs Charlie Flanagan have yet to publicly declare.
Senior figures in Mr Coveney’s camp insisted the game was still there to be won denying the numbers were falling in Mr Varadkar’s favour.
One told The Irish Times: "There are about 26 members of the parliamentary party. Those who have declared for Leo Varadkar and those who have declared for Simon Coveney will come as no great surprise to any.
“Richard Bruton was the only surprise. Those who think this is over are wrong.”
Mr Coveney’s campaign is confident it can secure the support of a large number of county councillors. It claims the backing of 28 out of 31 councillors in Cork and Kerry.
Mr Coveney formally lodged his nomination papers at Fine Gael headquarters yesterday and insisted he would fight a clean campaign.
He said he did not want to be an entertainer but a taoiseach who led the country to a united future.
Mr Coveney added: “I don’t think that a family living in a hotel room this evening is looking for a taoiseach with X Factor. They are looking for a taoiseach who’ll solve their problems.”
Asked how much he intended to spend on the contest, Mr Coveney insisted he did not know at this point.
However, he stressed he would not be spending vast amounts of money on the campaign. This follows calls by Mr Varadkar to impose spending limits on each of the contenders.
Meanwhile, Ms Fitzgerald confirmed she would not participate in the contest to replace Mr Kenny. The Irish Times understands the Tánaiste was seeking support to run until late on Wednesday night.
However, she announced her decision early yesterday morning confirming this was not the right juncture for her.
This was followed by the announcement by Mr Bruton, who confirmed he would not participate in the contest.
Mr Bruton’s intentions were unknown but he contacted Mr Varadkar and Mr Coveney before publicly declaring for the Minister for Social Protection.
Mr Bruton said he would not campaigning for Mr Varadkar and would not be making any further public comment on the leadership issue.
Fine Gael deputy leader Dr Reilly confirmed he would be standing aside from his role and declared for Mr Coveney.
Meanwhile, Fianna Fáil has insisted it is content with allowing the Fine Gael leadership contest to proceed.
Senior figures said the party would increase its preparations for a general election later this year should Mr Varadkar win the contest.
Several party members said Mr Coveney had proved himself willing to work with Fianna Fáil over the past year but Mr Varadkar had not been as forthcoming.
