Incoming prime minister Liz Truss has been urged to prioritise the restoration of powersharing in Northern Ireland by Sinn Fein’s Stormont leader Michelle O’Neill.

However, DUP leader Sir Jeffrey Donaldson instead insisted that Ms Truss should concentrate on resolving issues caused by the Northern Ireland Protocol, and added there could be no return to powersharing without “decisive action” on the post-Brexit arrangement.

Northern Ireland’s political leaders have been reacting following the news that Ms Truss has defeated Rishi Sunak in the race to be Conservative Party leader and the UK’s next prime minister.

It comes with the region in the midst of a political crisis after the DUP collapsed the Stormont institutions earlier this year in protest at the protocol, a special arrangement that keeps Northern Ireland in the EU’s single market for goods, avoiding a hard border with the Republic of Ireland.

However, the arrangement is deeply unpopular with unionists because it includes checks on goods moving between Great Britain and Northern Ireland.

The Government is progressing a Bill, introduced by Ms Truss, to give ministers powers to override parts of the agreement.

But Michelle O’Neill said it was time for UK Government to stop “pandering to the DUP” as she called for an urgent meeting with the incoming prime minister.

She said: “Liz Truss has an opportunity to come in now and stop pandering to the DUP, stop pandering to the approach which is damaging to our ability to help people through the cost of living crisis,” she said.

She urged the new prime minister not to suspend the protocol, by triggering Article 16 of the post-Brexit arrangements, and instead engage with the EU and Irish government to find a resolution to the issues with Irish Sea trade.

“What we need to see now is a change of tack, a change of policy, a change of approach,” Ms O’Neill said.

But the DUP leader said he had already written to the new PM asking her to prioritise progressing the legislation which deals with the impacts of the protocol.

Sir Jeffrey said: “Chief among those (priorities) is taking forward the bill which will provide a basis for a solution to deal with the protocol, to remove the barriers to trade between Northern Ireland and Great Britain, to fully restore Northern Ireland’s place within the UK internal market.

“So, in tackling the cost of living, the prime minister must continue to tackle the consequences of the protocol because we want to see that dealt with decisively.”

Sir Jeffrey said there was currently no cross-community consensus for the Stormont institutions to operate.

He said: “We will be saying to the prime minister that is why action is needed, that is why we need to see this legislation going through Parliament, and if there is to be renewed negotiation with the EU, then the prime minister needs to be very clear that for the institutions to be restored, decisive action is required to remove the barriers of trade and to respect the integrity of the UK internal market.”

Naomi Long, leader of the cross-community Alliance Party, said Liz Truss had a “window of opportunity” to make her mark on Northern Ireland.

She added: “As such, she can make a positive impact on Northern Ireland by engaging in sensible discussions with the EU around the protocol, and pursuing reforms to the Assembly and Executive in order to secure their return and future-proof both.

Ulster Unionist Party leader Doug Beattie said Liz Truss would be facing a “bulging in-tray”.

He said: “They need to find solutions and those solutions must help get our executive back up and running again because every day without an executive our people are suffering.”

SDLP Leader Colum Eastwood said there would be “no honeymoon period” for the new Conservative leader.

He said: “The age of prime ministers dancing to the tune of the DUP must now be over. Sabre-rattling with the European Union must give way to honest dialogue in the interests of all our people.”

Traditional Unionist Voice leader Jim Allister said any “sensible unionist would judge Liz Truss not by her words but by her actions”.

“First and foremost the challenge for the prime minister is to take back sovereignty over this United Kingdom and to end the ill-gotten sovereignty of the EU and restore Northern Ireland as a full and complete part of the United Kingdom,” he said.