Significant doubts exist within the Fianna Fáil National Executive about the Taoiseach's decision to push for Mayo TD Ms Beverley Flynn's expulsion from the party.
The Parliamentary Party whip is expected to be removed from Ms Flynn, who lost her appeal in her libel action against RTÉ on Wednesday, when TDs, Senators and MEPs meet next Tuesday.
However, the debate at the National Executive next Friday on a motion to expel her from membership of Fianna Fáil could prove to be a much tighter issue, although it is expected to succeed.
Rejecting her appeal against a High Court judgment, the Supreme Court found that she had encouraged and assisted others to evade tax during her time as an employee of National Irish Bank.
A large minority of National Executive members spoken to yesterday by The Irish Times privately opposed the Taoiseach's action, on the grounds that other TDs, including Mr Liam Lawlor and Mr Ray Burke, were not treated so harshly.
Speaking on RTE's Prime Time programme last night, Ms Flynn accused the Taoiseach of attempting to "pre-empt" next week's debates in both the Parliamentary Party and the National Executive.
"I seem to be carrying a very heavy burden on behalf of banking in this country. I do feel personally very let down," she said.
"They are almost being asked to rubber-stamp a decision by the Taoiseach," said Ms Flynn, who again denied that she had facilitated tax evasion during her time at National Irish Bank.
"It is an unprecedented step that they should try and force me out of the party," she told Prime Time.
The last senior political figure to be expelled from the party "for conduct unbecoming" was Mr Des O'Malley in 1985, following his decision to vote against Fianna Fail in the Dáil.
Despite some earlier doubts, Ms Flynn, who is understood to be deeply angered by Mr Ahern's decision to seek her removal from the party, will be able to present a defence of her actions directly to the National Executive.
The motion to be heard by the 95-strong National Executive, which will meet at 6.30 p.m. next Friday in Leinster House, proposes that she be expelled from the party "for conduct unbecoming".
A major effort will be launched over the coming days by senior party figures to get doubtful National Executive members onside, though some spoken to by The Irish Times insist that they will not change their minds.
The motion to go before the Parliamentary Party on Tuesday argues that in light of the Supreme Court judgment, Ms Flynn should lose the party whip "in the best interests of the party and the workings of Government".
Reflecting the views of many colleagues, one Fianna Fail TD privately said: "People accept that this is the way to go, given the current climate, but everybody also knows that she is being treated harshly."
Following a meeting with a party delegation from Mayo yesterday morning, the Taoiseach, Mr Ahern, defended his decision to seek disciplinary penalties against the TD.
"We're a democratic political party. We make the laws and pass the laws and we have to uphold them, and in this case a determination has been made by the Supreme Court," he declared.
"So, I'm afraid, as far as I'm concerned as leader of the party, I must follow the rules. Due process will be rigorously followed," he said, following his attendance at a Fianna Fail fundraising breakfast.
One National Executive member, who spoke on condition of anonymity, said: "Personally, I think this is wrong. She wasn't a public representative when this happened. She was taking orders from the bank," the individual declared.
However, a Cork-based National Executive member, Mr David Whyte, supported the Taoiseach's proposal: "I don't think that we should even have to travel to Dublin to deal with this. She should go. We were prepared to give her the benefit of the doubt, but that has gone."
However, one unhappy TD complained to The Irish Times, "We have had other people in difficulties and they were not thrown out. What is good for one should be good for all."
Already facing €2 million costs for her failed legal battle against RTÉ, Ms Flynn was yesterday told that she would have to pay the €100,000 bill incurred in her unsuccessful Supreme Court appeal.