The Northern Ireland Secretary of State has said that the British government will not be reopening negotiations on the Windsor Framework with the European Union.
The Windsor Framework was agreed by the European Union and the UK earlier this year as a way to reduce red tape on trade between Britain and Northern Ireland.
Chris Heaton-Harris held talks with leaders of the five main political parties in Northern Ireland since yesterday.
He said that "good progress" has been made and described his outlook as "glass half full".
Speaking at Hillsborough Castle in Co Down this afternoon, Mr Heaton Harris said the British government was working with the DUP to provide additional clarity on the basis on which the party would return to the Northern Ireland Executive.
He said he believed there was a "genuine willingness on all sides" to "establish the conditions for the devolved institutions to work and thrive".
Mr Heaton-Harris said that the discussions were not about money and that it "goes without saying" that the Windsor Framework agreement would not be subject to renegotiation with the EU.
"I remain deeply cognisant of the delicate balance to the Belfast Good Friday agreement and completely understand the sensitivities and shared ownership of these issues", he said.
He said he would not discuss timelines for these discussions but that he would "like to think" that substantial progress could be made in the next few weeks.
Mr Heaton-Harris said that while parliament will be going into recess, this work will not.
He added: "We have an opportunity now to make sure we get the Executive up and running on a basis that is sustainable for the long term in Northern Ireland. That's what I want to achieve.
It is taking a lot longer than I would have liked, maybe not as long as I expected it to, but this is important to get right."
Stormont stalemate 'totally unsustainable' - O'Neill
Meanwhile, Sinn Féin vice president Michelle O'Neill has said the ongoing Stormont stalemate is "totally unsustainable".
Following a meeting with Mr Heaton-Harris, Ms O'Neill said engagement would continue, but stressed it had to be meaningful and lead to the restoration of the devolved powersharing institutions.
The DUP has insisted it will not return to Stormont until the British government provides further legislative assurances around Northern Ireland's place within the UK internal market.
Senior civil servants have been left running Stormont departments and face having to make substantial cuts following a budget set by Mr Heaton-Harris.
Following her meeting, Ms O'Neill said the British and Irish governments have to do more to bring Stormont back.
She said: "We have just had our meeting with the secretary of state and we have made it very clear to him that the current position is totally unsustainable, this vacuum isn't good enough, all it is serving is to punish the public."
Ms O'Neill added: "Whilst people within the DUP take themselves off on summer holidays, workers and families are left struggling and worrying about how they are going to deal with the cost-of-living issues.
"We have impressed upon the secretary of state that both himself, the British government and the Irish Government must do more; this position just isn't tenable.
"We need to see action, the public rightly expect that everybody will work together."
"We have heard from the secretary of state that they intend to be engaged over the summer, but there is a difference between engagement, and engagement which is actually meaningful and leads to a restoration of the executive."
DUP leader Jeffrey Donaldson said after his meeting yesterday that the "ball is in the government's court" with regards to action which would see the restoration of powersharing.
Mr Donaldson said there had so far been a "lack of meaningful action" from Westminster in addressing his concerns over post-Brexit trading arrangements.
Mr Heaton-Harris has been pressing the parties on their plans for a costed programme for government for any incoming executive.
