"The pro-life movement must try to work with people of goodwill all across the political spectrum to try to restore the culture of life," he said. "No political order lasts forever."
The party does not yet have a name. Its draft manifesto emphasizes housing, healthcare and education as human rights, while also backing fair wages for workers, "healthy functional enterprise," economic incentives for risk-takers and investors, and an end to the excessive concentration of wealth. It is described as "Euro-critical" and opposed to European federalism and a European army. While Toibin's future in Sinn Fein suffered from strict party discipline, the draft manifesto promises respect for the consciences of lawmakers.
Toibin has said the manifesto is subject to change as the party broadens its engagement.
In Kelly's view, a new pro-life political movement "will have to be a 'broad church' and one that can appeal to people from various political backgrounds." The pro-life vote is "very fractured at the moment."
"Many pro-life voters remain reluctant voters for their traditional political party," he said. Many people vote for the party that their families voted for, a habit that dates back to the Irish Civil War of 1922-1923.
"There is some evidence that this is changing and that people are willing to set aside old tribal loyalties," said Kelly.
Sinn Fein competes in both the Republic of Ireland and Northern Ireland, which is under the government of the United Kingdom but has significant self-governing powers, including over abortion law.
The repeal of the Irish pro-life amendment has led to renewed efforts to expand abortion in Northern Ireland.
"All of the reputable polling indicates that this is opposed by the majority of citizens there," said Kelly. "The spectacle of politicians in Dublin and London trying to impose abortion on Northern Ireland when the very heart of the 1998 peace agreement was that the people of Northern Ireland-and only the people of Northern Ireland-should decide the political direction of the region is appalling."
Toibin appears to have some political support on both sides of the political border.
Declan McGuinness of Derry, the brother of Martin McGuinness, a leading Sinn Fein politician and former deputy first minister of Northern Ireland, has said he is working with Toibin.
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In the Republic of Ireland, his movement has signed up two former Sinn Fein county councillors, the Irish newspaper The Journal reported Wednesday.
The organization has planned several open meetings around Ireland to develop the organization.
Sinn Fein leader Mary Lou McDonald, who succeeded the retiring Gerry Adams at the last party convention known by its Irish name, the Ard Fheis, voiced regret at Toibin's resignation and said he was "a valued member of the the party."
"Sinn Féin is home to a diversity of views; we debate and our members vote on policy at our Ard Fheis," she said, adding that all elected representatives of the party are bound by its decisions.
Citing voter approval of the Eighth Amendment repeal, she said party members in parliament have the responsibility "to give effect to the people's vote and to represent Sinn Fein policy," the Irish newspaper the Independent reports.
"Unfortunately Peadar was unable to do this and was suspended from the party and has now taken the decision to resign."