Joe Biden called for the restoration of powersharing government at Stormont during a speech in Belfast.
The US president said he hopes the assembly and executive will “soon be restored” in an address at Ulster University.
Unionist party the DUP has boycotted the Northern Ireland assembly for a year over concerns about the Brexit deal known as the Northern Ireland protocol.
Rishi Sunak has a new deal, dubbed the Windsor Framework, aimed at addressing concerns about sovereignty and breaking the deadlock. However, members of the DUP argue it does not go far enough.
Biden told the audience an “effective, devolved” government that reflects the people of NI would help draw “even greater opportunity” to the region.
“I hope the assembly and the executive will soon be restored,” he said.
“That’s a judgment for you to make, not me. I hope it happens, along with the institutions that help facilitate north-south and east-west relations, all of which are vital pieces of the Good Friday Agreement.”
Biden said Brexit had created “complex challenges” for NI but praised the leadership of Sunak and European commissioner Ursula Von der Leyen to reach an agreement.
“The Windsor Framework addresses the practical realities of Brexit and it is an essential step to ensuring the hard-earned peace and progress of the Good Friday Agreement that they are preserved and strengthened,” he said.
“Negotiators listened to business leaders across the UK and Ireland who shared what they needed to succeed, and I believe the stability and predictability offered by this framework will encourage greater investment in Northern Ireland, significant investment in Northern Ireland.”
The government won support in parliament for part of its new Brexit deal by 515 votes to 29, despite a rebellion from some of its own MPs and a backlash from members of the DUP.
The UK government has issued a veiled warning that it will consider direct rule from London unless the region’s biggest unionist party ends its boycott of the power-sharing executive soon.
DUP leader Jeffrey Donaldson said Biden’s remarks would not change the political dynamic.
“Well, it doesn’t change the political dynamic in Northern Ireland, we know what needs to happen,” he said.
“And I’ll be meeting my team over the next few days and we’ll be going back to the (UK) government. We believe the government needs to go further in terms of protecting Northern Ireland’s place within the United Kingdom and our ability to trade within the UK internal market and that’s what needs to happen now to enable us to move towards the restoration of the political institutions, we need the government to deliver what they’ve said they will do, which is to protect our place in the United Kingdom.”