Peter Hain has said the weeks leading up to the government's devolution deadline will present local politicians with a great opportunity and challenge.
NI parties have a great opportunity to progress, Peter Hain says
The Northern Ireland secretary was writing in the Daily Mirror.
He says the parties have worked together on the Stormont preparation for government committee without compromising their principles.
Mr Hain says if there is no deal the politicians will have to explain to voters why.
The opportunity for local people to have a say in how they are governed could be passed up potentially for years to come, he adds.
The deadline for restoring devolution is 24 November.
On Monday, a spokesman for Prime Minister Tony Blair said he believed genuine progress had been made in bringing the local parties together to prepare for government.
Mr Blair's official spokesman said the next few months would be "one of the most important periods in Northern Ireland that we have seen for some time".
"This autumn will reflect that and the level of the meetings we have will reflect that," he said.
"We have seen some genuine progress in terms of the parties taking the preparation for government seriously."
The spokesman said cooperation would now "need to be taken to a new phase".
Devolved government was suspended over allegations of a republican spy ring.
The court case that followed collapsed and one of those involved, Denis Donaldson, later admitted working as a British agent.
Direct rule from London was restored in October 2002 and has been in place since.