Offaly TD Carol Nolan has confirmed she has left Sinn Féin.
The Irish Times has learned Ms Nolan has written to the party informing them she will not be returning to Sinn Féin.
She had been on a three-month suspension for voting against a Bill to hold a referendum to repeal the Eighth Amendment.
The party voted against a vote of conscience on abortion policy at its ardfheis at the weekend.
In a statement, Ms Nolan said she felt it was “unethical to force TD’s who were strongly opposed to abortion to vote against their conscience”.
“I do not want to have any hand, act or part in bringing about the end to the life of an unborn child, the most vulnerable in our society. It is not for politicians or society, in general, to decide who lives or dies.
“Every life is precious and every child deserves the chance to live. I don’t believe that abortion is the solution to any crisis. How can it be when it takes the right to life away from the unborn?
“I cannot and will not support abortion and for that reason I have made a decision to leave Sinn Féin.”
Sinn Féin leader Mary Lou McDonald said the resignation “is disappointing but not surprising”.
Ms McDonald said the party has made “every effort to give its members space and latitude to articulate a position contrary to the party’s position in the recent referendum campaign on repeal of the Eighth Amendment”.
“The people have spoken on this issue. The Sinn Féin ardfheis has democratically agreed the party’s position to support the forthcoming leglislation.”
