Taoiseach Brian Cowen is set to go toe-to-toe with rebel ministers in the fight for leadership of his ruling Fianna Fail party.
Both Mr Cowen and the number one challenger, foreign affairs minister Micheal Martin, claim they have the support to take control.
Mr Cowen secured the backing of transport minister Noel Dempsey, but two other senior Cabinet colleagues refused to declare their hand.
Finance minister Brian Lenihan and tourism minister Mary Hanafin - both potential leadership candidates - are expected to reveal their voting intentions later.
Mr Cowen will break with tradition and put forward a motion of confidence in himself as leader of Fianna Fail. He needs 36 TDs to support to retain control.
The Taoiseach said Fianna Fail was in a fight for public support and that he was the fighter it needed. He said: "I remain confident obviously of the outcome."
"I think my decision to have a confidence vote will enable us to put this matter to rest once and for all for the foreseeable future.
"From my point of view, it is clearly the case that the settled view of the party is that I should lead Fianna Fail."
More than half the voting TDs declared their hand and although up to 20 would not discuss their intentions or did not return calls, Mr Cowen insisted he had the numbers.
Mr Martin - the taoiseach's main challenger - claimed a change in leader would put fire in the belly of party workers and supporters. He said there had not been a "heave" in the traditional political sense but that senior party members wanted Mr Cowen to move aside.