Rishi Sunak's appointment as Conservative party leader and next prime minister has received a mixed response in Northern Ireland with unionists calling on him to "deal with the protocol".
Sinn Fein called for the end of the brinkmanship in NI and for the DUP to return to power-sharing. Alliance reiterated its call for power sharing to be reformed.
SDLP leader Colum Eastwood launched a scathing attack on the incoming prime minister saying he had no mandate and it was time for a Labour government to "repair the damage". The Foyle MP said it was time "for the adults to take over".
Mr Eastwood was one of many reacting to the appointment of Mr Sunak following the resignation of Liz Truss last week.
Mr Sunak was crowned Conservative leader at lunchtime on Monday after his closest rival Penny Mordaunt withdrew from the contest.
Among the many issues facing Mr Sunak when he enters No. 10 is an impending Assembly election in Northern Ireland. The current Secretary of State has said - as the law states - he will be forced to call an election on Friday if power-sharing is not restored.
The DUP congratulated the former Chancellor on his new role.
However, Sir Jeffrey Donaldson made clear what they expected from the new PM on the Northern Ireland Protocol.
He said the mechanism - agreed between the EU and UK to avoid a hard border between Northern Ireland and the Republic was "incompatible with the restoration of devolved government".
"If the prime minister wants to see a fully-functioning Stormont, then he must deal with it once and for all," he said.
"Delivering that solution would be a very powerful signal that he is focused on building a better future for everyone."
Speaking before the announcement, Sinn Fein president Mary Lou McDonald urged the DUP to return to the Executive and outlined her party's support for the protocol.
"MLAs must get to work and do the job they are elected to do," she said.
"The protocol can work better. That is the stated position of the EU, the current British Government, the US administration, the Irish Government and the rest of us support that end, sooner rather than later, through a negotiated settlement.
"Continuing to block the formation of an Executive, and preventing an Executive doing its best to help people through this extremely difficult time, is unacceptable."
UUP leader Doug Beattie said one of the new prime minister's priorities had to be resolving the political impasse in NI.
"Northern Ireland cannot continue to be used as a political football between the United Kingdom and the EU," he said.
"The protocol must be replaced with a deal that works for everyone. There should be no checks on goods moving between Great Britain and Northern Ireland that are staying here.
"Everyone knows what needs to be done, and now is the time to be getting on with it."
The Alliance party also congratulated Mr Sunak, however, Naomi Long again called for reform of the power-sharing institutions.
"The protocol is only the latest in a long line of grievances to have collapsed Stormont," she said.
"Until the institutions are reformed to remove the vetoes the largest parties wield over Executive formation, the crisis-collapse cycle will continue."
Ann McGregor, chief executive of the Northern Ireland Chamber of Commerce and Industry, congratulated the Mr Sunak.
She urged him to do all he could to restore devolution in Northern Ireland.
"He will assume the role during an exceptionally challenging time," she said.
"Businesses will hope his appointment will lead to the economic stability and political certainty that is so urgently required.
"Given the significant fiscal pressures we face and with only days left until Northern Ireland could find itself without devolved ministers, we would urge the new prime minister and the UK Government to do all that they can, without delay, to work with local parties to restore a fully functioning Executive."
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