US president George W Bush has urged Northern Ireland's political parties to work together to restore the power-sharing government.
President Bush has urged politicians to give leadership
His comments came after the British and Irish prime ministers unveiled a blueprint for reviving devolution.
Assembly members have been given until 24 November to set up an executive.
In a statement from the White House, Mr Bush urged politicians to "demonstrate leadership" to resolve the outstanding issues.
"Today is an opportunity for all in Northern Ireland to take control of their future and bring the political process to a successful completion this year," the White House said on Thursday evening.
"President Bush calls on all parties to demonstrate leadership and seize this opportunity to work together to restore the power-sharing government and resolve outstanding issues.
Assembly recalled on 15 May: politicians given six weeks to form executive
If this fails, further 12 weeks after summer recess to form executive
If this is not achieved by 24 November deadline, assembly members' salaries and allowances stopped
Governments would then work on partnership arrangements to implement the Good Friday Agreement
"We remain steadfast in our support of the peace process and the efforts of the British and Irish governments to achieve a lasting peace under the principles of the Good Friday Agreement."
Tony Blair and Bertie Ahern travelled to Northern Ireland on Thursday to give parties a "take-it-or-leave-it" plan.
The assembly is to be recalled on 15 May with parties being given six weeks to elect an executive.
If that fails, the 108 members get a further 12 weeks to try to form a multi-party devolved government. If that attempt fails, salaries will stop.
The British and Irish governments would then work on partnership arrangements to implement the Good Friday Agreement.
Mr Ahern has acknowledged the difficulties facing himself and Mr Blair were compounded by the murder of ex-Sinn Fein official and former British spy Denis Donaldson in County Donegal.
The IRA has denied involvement.
Mr Blair said it was "a moment to let the process be governed, not by suspicion but by the faith that the other does want this to succeed."
Mr Ahern said the politicians have been given a "finite" time to reach agreement.
Devolved government at Stormont was suspended in October 2002 following allegations of a republican spy ring.
Mr Donaldson was one of three men later acquitted of charges linked to those allegations.