BELFAST - Northern Ireland’s bickering leaders came under pressure Sunday to unite in a new government after the Irish nationalist party Sinn Fein secured an unprecedented election win.

Once the political wing of the paramilitary IRA, Sinn Fein won enough seats in the devolved legislature to nominate its Northern Ireland leader Michelle O’Neill as first minister.

The result from Thursday’s election for the Stormont assembly marked a potentially seismic shift, a century after Northern Ireland was carved out as a Protestant fiefdom under British rule.

O’Neill said the result “ushers in a new era” for the divided territory, and Sinn Fein said it wanted a referendum on reuniting Ireland within five years.

But only the UK government can grant a referendum, and Justice Secretary Dominic Raab noted that 58 percent of voters had backed parties committed to the UK union or the constitutional status quo.

Northern Ireland’s people all want “stability”, he told Sky News, demanding that the European Union agree to changes to post-Brexit trading rules that have become anathema to pro-UK unionists.

“I think it’s equally clear that that stability is being put at risk, imperilled, by the problems with the Northern Ireland Protocol,” Raab said. Equally for the UK government, he said, “We want to see an executive formed” in Belfast, for “the parties to come together to provide the people with that stability.”

The Irish and US governments also urged Northern Ireland’s leaders to form a new power-sharing executive, under the terms of a 1998 peace deal that ended three decades of bloodshed.