LONDON — Northern Ireland got new government leaders on Thursday after the two biggest parties broke a standoff that had threatened to scuttle the Protestant-Catholic power-sharing administration.

But the move inflamed tensions inside the pro-British Democratic Unionist Party, as party legislators, angry at not being consulted, tried to block party leader Edwin Poots from appointing a new first minister.

Poots went ahead and nominated Paul Givan, who was confirmed by the Northern Ireland Assembly as first minister. Michelle O’Neill of Irish nationalist party Sinn Fein was reappointed deputy first minister.

Accepting the nomination, Givan said politicians “must recognize there is more in common than separates us.”

But his own party was deeply divided. The party’s officers met Thursday afternoon amid anger at Poots, who has been leader for only a month, for what some saw as caving in to Sinn Fein pressure.

Sinn Fein had threatened not to fill the post of deputy because of a feud about protections for the Irish language. That would have mothballed the administration — under the power-sharing arrangements set up as part of Northern Ireland’s peace accord, a government can’t be formed unless both roles are filled.

The language issue cuts to the heart of tensions between Northern Ireland’s mostly Catholic nationalists, who see themselves as Irish, and Protestants, who largely identify as British.

The Northern Ireland Assembly, in which the DUP is the largest party, has failed to pass a law ensuring protections for the Irish and Ulster Scots languages, despite the power-sharing parties agreeing last year to do so.

But after crisis talks with the two parties, the British government said early Thursday it would step in and pass the legislation in the UK Parliament if the Belfast assembly did not do it by September.

Sinn Fein welcomed the move, with party leader Mary Lou McDonald saying it had broken the “logjam of DUP obstructionism.” Poots accused Sinn Fein of creating instability, but agreed to nominate a first minister.

The new government was formed following the resignation of Arlene Foster as first minister and DUP leader. She quit in April, under pressure from her party over her handling of Brexit and her perceived softening on social issues such as abortion and LGBT rights.

By the narrowest of margins the party elected Poots, a social and religious conservative, to replace Foster as leader. He broke with tradition by deciding not to serve as first minister.

He could now face a challenge to his leadership.

“You cannot lead people who are not following you,” DUP lawmaker Sammy Wilson said as he entered Thursday’s party meeting. “If you have no followers, you can’t be a leader, can you?”

The DUP, which is rooted in the fundamentalist Free Presbyterian Church, opposed Northern Ireland’s 1998 peace accord. It later became reconciled to it and has shared power with the Irish Republican Army-linked Sinn Fein.

Poots is a Christian fundamentalist and believer in creationism whose conservative views on social issues echo those of the DUP’s founder, the late Rev. Ian Paisley.

The British government retains an array of powers affecting Northern Ireland, but the Belfast assembly can make laws in areas including agriculture, education and health.

The power-sharing relationship has often been strained, and Britain’s economic split from the European Union at the end of 2020 has further shaken the political balance in Northern Ireland.

Post-Brexit trade rules have imposed customs and border checks on some goods moving between Northern Ireland and the rest of the UK, angering Northern Ireland’s British unionists who say the new checks amount to a border in the Irish Sea and weaken ties with the rest of the UK.

Tensions over the new rules contributed to a week of street violence in Northern Irish cities in April that saw youths pelt police with bricks, fireworks and gasoline bombs.