Secretary of State Peter Hain has warned he needs an answer from Northern Ireland parties by 25 March if 26 March deadline for devolution is to be met.
NI Secretary Peter Hain said time was critical
He was speaking on the second day of counting in the Northern Ireland Assembly elections.
The DUP and Sinn Fein have taken more than half the first preference votes between them in the assembly election.
Mr Hain warned the assembly would close if the parties did not sign up to power sharing in the next two weeks.
Most of the 108 assembly seats have now been decided. Mr Hain met Sinn Fein on Friday and is to meet the DUP.
Earlier on Friday, prime ministers Tony Blair and Bertie Ahern said in a joint statement that voters in Northern Ireland had issued a clear message they want devolved government back.
As a second day of counting got under way, the premiers said: "Restoration of the devolved institutions represents an opportunity of historic proportions."
However, DUP deputy leader Peter Robinson said conditions had to be right for his party to go into government with Sinn Fein.
"When the conditions are met, the Democratic Unionist Party is ready," he said.
"It is up to other people to meet the requirements as soon as it is possible. Let them get on with it and stop dragging their feet."
The DUP got 30.1% of first preferences - up 4.4% from 2003 - while Sinn Fein got 26.2%, up 2.6%.
Almost 250 candidates were standing in 18 constituencies in the proportional representation election.
The leaders of the four main parties were all returned, the DUP's Ian Paisley and Sinn Fein's Gerry Adams topping the polls in North Antrim and West Belfast respectively.
SDLP leader Mark Durkan was elected on the first count at Foyle, but UUP leader Sir Reg Empey had to wait to the third stage before being returned in East Belfast.
In third place in first preferences, the SDLP received 15.2% of first preferences, the Ulster Unionists 14.9% and Alliance 5.2%.
Ulster Unionist leader Sir Reg Empey said he would have liked more seats but respected the electorate's decision.
"Our commitment to devolution and a functioning executive has been made clear in the election campaign.
"We now wait to see if others will deliver devolution or the stagnation of continued direct rule," he said.
Meanwhile, UK Unionist Party leader Bob McCartney has lost his North Down seat in the Northern Ireland Assembly election.
UKUP leader Bob McCartney has lost his seat
Mr McCartney, a former MP for the area, had stood in six different constituencies across Northern Ireland.
His vote in north Down was half of what he achieved in the previous election. He secured just 1806 votes and was eliminated on the seventh count.
Meanwhile, speaking after a meeting with Mr Hain on Friday, Sinn Fein leader Gerry Adams said: "We look to both governments to accept what the people overwhelmingly voted for.
"That is for local politicians who sought a mandate to execute that mandate in the institutions of the Good Friday Agreement."
SDLP leader Mark Durkan said it was important to take the situation forward.
"We need to work with the mandates that the parties have, we need to try and convert that into working political institutions."
The Alliance Party leader David Ford said he thought a lot of people had grave doubts about whether the DUP and Sinn Fein were willing to share power constructively.
Lady Sylvia Hermon, the Ulster Unionist Party's only MP, criticised her party's performance in the assembly election.
Speaking at the count in North Down, she said her party's vote management had been "woeful, to put it mildly", and added that she had "a lot to think about".
The Northern Ireland Assembly has been suspended since October 2002, amid allegations of an IRA spy ring at Stormont. A subsequent court case collapsed. Direct rule has been in place since that date.
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