DUBLIN (AP) — Irish voters are choosing their next prime minister in an election where frustration with economic austerity and a housing crisis have fueled the rise of Sinn Fein, still shunned by the country's main political parties because of its links to the Irish Republican Army.

Voting stations opened at 7 a.m. (0700 GMT) on Saturday and a national exit poll is expected to be released shortly after they close at 10 p.m. The last pre-election opinion polls showed Sinn Fein in a virtual dead heat with Prime Minister Leo Varadkar's Fine Gael and the opposition Fianna Fail, the two parties that have dominated Irish politics since independence.

Surging support for Sinn Fein, which is committed to the reunification of Ireland, threatens Ireland's political equilibrium even though the party is unlikely to form the next government because both Fine Gael and Fianna Fail refuse to work with it.

Sinn Fein is a major force in Northern Ireland, which is part of the U.K., but has long been a minor political player in the Republic, shunned by the bigger parties because of its ties to the IRA. But the party’s left-wing proposals for tackling Ireland's housing crisis and creaking health care system are striking a chord.

“I do think there is need to change,’’ said Noleen Kelly, 50, who works in the public sector, outside a Dublin polling station. “So I’m looking forward to see something positive.’’

The two big parties, whose origins lie on opposing sides of Ireland’s 1920s civil war, are fierce rivals but share a broadly center-right outlook. For decades power has alternated between them.

But support for the two parties has fallen since the 2008 global financial crisis, which hit the debt-fueled "Celtic Tiger” economy particularly hard. Ireland was pushed to the brink of bankruptcy and forced to seek a humiliating international bailout that was followed by years of austerity.