Prime Minister Theresa May and Taoiseach Leo Varadkar will arrive in Belfast today as Sinn Fein and the DUP hammer out the final details of a deal to restore power-sharing.
The two leaders will meet Northern Ireland's five main political parties during their visit which is seen as a strong sign that a talks breakthrough is imminent.
The Belfast Telegraph exclusively revealed last Thursday that Sinn Fein and the DUP were very close to a deal, which sees significant compromise by both sides to end the political stalemate.
Talks sources last night described today as a "huge day" in the negotiations.
A Downing Street spokesman said Mrs May would take part in a series of meetings at Stormont House, and encouraged Sinn Fein and the DUP to resolve their differences.
A spokesman for Mr Varadkar said that he and Mrs May would assess the state of play in the negotiations between the two parties.
In a sign that the dynamic at Stormont has significantly shifted gears, the Taoiseach cancelled a scheduled meeting with Welsh First Minister Carwyn Jones in Dublin today in order to head to Belfast.
There is speculation that the Government may offer Northern Ireland additional funding if the DUP and Sinn Fein finalise a deal.
Downing Street said Mrs May will tell the parties that her Government is ready to introduce legislation to enable the re-establishment of the Stormont institutions as soon as possible if an agreement is sealed.
Ahead of the meetings at Stormont, the Prime Minister will visit a local business to meet staff and management.
Talks between the two biggest parties were suspended over the weekend as Sinn Fein members met in Dublin to endorse Mary Lou McDonald as their new president. However, bilateral discussions will resume today.
A Stormont source said: "While the visit by the British Prime Minister and the Taoiseach is most welcome, the DUP and Sinn Fein can best spend their time talking to each other rather than to Theresa May and Leo Varadkar."
The two Governments have been largely locked out of this current round of talks with the two big parties hammering out a potential deal themselves.
SDLP leader Colum Eastwood welcomed signals that a deal was finally within reach. He explained that his party would await "the publication of its detail before giving full judgment".
Mr Eastwood said: "For over a year the people of the north have been badly let down. Having been frozen in failure for over a year, a deal must not be a moment of self-congratulation for Sinn Fein and the DUP.
"If a deal is done, it must instead be a moment when our politics returns to the real challenges and crises facing this society."
The SDLP leader added: "People understand that simply forming a new Executive is not in itself enough.
"The real change necessary is an end to the cycle of two parties who have proved themselves very good at the art of political stand-off but very bad at the responsibility of government.
"That is the joint DUP/Sinn Fein status quo that must now end.
"Any new government must use its power to tackle the real challenges faced by this society, it must be a new government which ends the decade-long pattern of DUP intransigence and Sinn Fein weakness, and it must be a government which proves itself of actual relevance and value to all our people."
TUV leader Jim Allister said it was clear Sinn Fein would return to the Executive only "on their terms" and he described the DUP's "desperation to get back into office in a failed system" as laden with danger.
Mr Allister said there was "no justification whatsoever for any further concessions" on the Irish language.
"Irish is already more than generously feted. Any legislation to promote it further - whether it is called an Irish Language Act or a Cultural Act wrapped up in tartan ribbon - will monumentally aid the Sinn Fein agenda of destabilising Northern Ireland," the North Antrim MLA claimed.
"Rights-based recognition will be a vehicle, whatever the DUP might pretend, to hallow out our Britishness and turn the public service into a cold house for unionist," he added.