EUROPEAN Affairs Minister Lucinda Creighton is to resign as European Affairs Minister after voting against the Government on an amendment to the abortion bill.
Ms Creighton also lost the party whip and faces an uncertain future in the political wilderness.
The Dublin South East TD voted against the Government on the controversial suicide clause to the abortion bill.
She becomes the fifth and final Fine Gael TD to rebel against the Coalition, and cast her decisive ballot on the second day of the abortion debate.
Ms Creighton follows Billy Timmins, Terence Flanagan, Brian Walsh and Peter Mathews in rebelling against Taoiseach Enda Kenny, who had imposed tough discipline on Fine Gael in the lead up to the vote.
Speaking after her decision, Ms Creighton said: "It's very disappointing and I would rather that I wasn't here. For me, this is a very important piece of legislation, one which is against a commitment that we made at the last election - a promise had been made, a very fundamental promise - on abortion.
"I just felt that I couldn't remove from that promise that we made at the last election," she told RTE News.
When asked whether or not she had been willing to compromise on this issue due to the nature of a coalition Government, Ms Creighton said it "was not possible" to compromise on matters of "life and death".
"Well, I think compromise is essential to any coalition. I feel we've compromised on economic issues, social policy and so on," she added. "But when it comes to something that is a matter of life and death, at least as far as I'm concerned it is, I think it's not really possible to compromise. I think everybody in the Oireachtas agreed that it was necessary to put in some legal certainty, whether by legislation or regulation to doctors in providing full medical support for women in pregnancy, to ensure their lives would be saved, we all supported that. But this went further than that."
It also means the 33-year-old's future in the party is unclear, since Mr Kenny also said anyone who voted against the Government could not run for Fine Gael at the next election.
Ms Creighton and Mr Kenny have long had an uneasy relationship, and she voted against him and supported Richard Bruton in the 2010 heave.
They have clashed since then and Ms Creighton had expressed her unease with the measures in abortion the bill for months, and she had particular problems with the suicide clause.
She eventually voted against the Coaliton on amendment 56 to the abortion bill, which was on the suicide clause and was tabled by Mr Timmins, Mr Flanagan, Independent TD Mattie McGrath, Sinn Fein's Peadar Toibin and Fianna Fail's Eamon O Cuiv.
The Coalition won the vote by 130-24, and Ms Creighton cast her vote just before nine o clock last night.
The dramatic moment which marked the most high profile TD to leave Fine Gael since Enda Kenny became Taoiseach took place on the second day of the debate on the Protection of Life During Pregnancy Bill.