The UK Government has restated its commitment that parties from all sides will be called to elect members to a governing executive on Thursday.

But BBC Northern Ireland Correspondent Tom Coulter says the two sides are as far apart as ever.

When called to form the cabinet at Stormont, it seems almost certain that Mr Trimble will refuse to nominate members from his party, he says.

Agreement review

BBC Ireland Correspondent Denis Murray: "Mr Blair doesn't believe the door to the process has been slammed"

That means the workings of the Good Friday Agreement will be suspended, sparking a review mechanism.

"They can make decommissioning the sole focus of the review mechanism, and that's what they want," Mr Coulter told BBC News 24.

"It means they can almost renegotiate the whole decommissioning process.

BBC Ireland Correspondent Denis Murray: "It is not quite back to step one"

"They are digging their heels in and saying no change to our policy, and that policy is 'no guns, no government'."

Lords adjournment

Failure to set up a cross-community executive means the House of Lords' debate on key legislation relating to the peace agreement will probably also be adjourned.

Jonathan Moore, professor of Irish Affairs at North London University, said it was difficult to be optimistic in this situation.

But he predicted an attempt to rebuild the resolve for a democratic way forward.

He pointed out that under the Good Friday Agreement, there have been developments elsewhere.

'Immense' progress

"The progress on other issues has been immense. We actually have a unionist party which is prepared to sit down with Sinn Fein, in theory," Mr Moore said.

The BBC's Ben Brown looks at the economic effects the troubles have caused

"We have a republican movement, which although it won't actually admit it, in practical terms is accepting that Northern Ireland will remain part of the United Kingdom while the majority so desire.

"The real problem is that when the Good Friday Agreement was signed, decommissioning played a very, very small part in it.

"However, in order to get David Trimble on side Tony Blair made private assurances to David Trimble that decommissioning would have to occur.