Liz Truss held her first official meeting with Joe Biden on Wednesday night as it emerged that Britain has set a six-month deadline to solve the impasse around the Northern Ireland Protocol.
Success could also pave the way for a major visit by the US president to the UK next April, as he is believed to want to take part in events celebrating the 25th anniversary of the Good Friday Agreement.
Meeting in New York, the Prime Minister and the US president discussed issues around the Protocol, which has plagued relations between the UK and Ireland since the signing of the Brexit withdrawal agreement.
The Northern Ireland Executive is currently suspended after the Democratic Unionist Party (DUP) withdrew from Stormont as a result of its objections to the Protocol.
British officials believe they have until the silver anniversary of the Good Friday Agreement, which was signed on April 10 1998, to solve the Protocol issue; a move which would allow the restoration of the Northern Ireland institutions.
Speaking before the bilateral meeting, Mr Biden told Ms Truss: “We are both committed to protecting the Good Friday Agreement of Northern Ireland. And I’m looking forward to hearing what’s on your mind.”
She replied: “Of course, I’m looking forward to discussing the Belfast Good Friday Agreement and how we make sure that’s upheld into the future.”
Mr Biden congratulated Ms Truss on becoming Prime Minister, adding: “I look forward to working closely with you. You’re our closest ally in the world and there’s a lot we can continue to do together.”
The agreement, which forms the basis of the province’s current system of devolved government, is seen in the US as a significant foreign policy success.
Any trip by Mr Biden would not technically be a state visit because King Charles III will not have been crowned by then.
However, the visit would provide an opportunity for the new King to meet the US president.
One senior diplomatic source said: “If you look at the calendar, you will conclude that next year might be an obvious reason to visit Europe if things come good.”
Another government source said: “What we want to do is protect and restore the Good Friday Agreement. And both of us [Britain and the US] are looking at the 25th anniversary next year as a key decision point, but the big obstacle to that being the lack of an Executive at the moment.
“The 25th anniversary is a key pivot moment, which is Easter next year. If you don’t have an Executive Assembly by then, that’s pretty bad all round.
“It’s an important place in the electoral cycle, for the Biden administration as well... So that’s the kind of primary focus which is an absolutely shared focus.”
A Downing Street spokesman said of the meeting: “On the Northern Ireland Protocol, the Prime Minister and president Biden both agreed that the priority must be protecting the Belfast (Good Friday) Agreement and preserving the gains of peace in Northern Ireland.”
Currently, the devolved government in Ulster, based at Stormont in Belfast, is suspended as part of the DUP’s protest against the Northern Ireland Protocol.
British officials hope that a deal can be reached between the political parties to ensure Stormont is up and running before the 25th anniversary celebrations.
It means that, in effect, the Government wants the impasse over the Northern Ireland Protocol to be resolved in the next six months.
The meeting with Mr Biden lasted 75 minutes – 15 minutes longer than scheduled. The tone was said to be “very warm”, with the discussion on the Protocol only a small part of it.
Ms Truss also held a private one-on-one meeting with Ursula von der Leyen, the president of the European Commission.