Outside the red brick two-storey building in Belfast's Glengall Street, one Ulster Unionist MP, Willie Thompson, promised that the campaign to oppose the settlement would go on and declared bluntly: "David Trimble's days are numbered."
Then Willie Ross, the parliamentary party's elder statesman and critic of the deal, was asked by newsmen why he was so opposed to the Stormont agreement. "Go and read it, gentlemen," he replied.
Mr Trimble's party executive backed him by 55 votes to 23 but he may now be in a minority of his 10-strong parliamentary party in proposing the deal. Jeffrey Donaldson walked out of the talks last week making his objections clear and two other MPs, Roy Beggs and Clifford Forsythe are thought to be hostile. Even the party's chief whip Martin Smyth, will be having grave doubts. Potentially that leaves just four MPs, including the party leader, advocating a "yes" in May's referendum.
With the full council due to vote on the deal on Saturday and Ian Paisley's DUP firmly opposed to the agreement, Mr Trimble's role is crucial in harnessing unionist support for the "yes" campaign.
For Mr Trimble this predicament is not as dire as it seems. After all he has rarely had the full backing of his fellow MPs. Indeed, when he was elected in 1995 not one of the MPs or office holders is thought to have voted for him.
A fully-fledged split, or a set of defections to Mr Paisley's Democratic Unionist Party is unlikely. Mr Ross, set to emerge as the leading critic of the settlement, is an Ulster Unionist loyalist who would abhor the notion of joining another party. Nor do he and Mr Paisley see eye to eye.
Mr Trimble will, however, have difficulty in managing his party at Westminster. His argument that opponents have lost the debate and should stick with the majority view is unlikely to prevail among men who were disgruntled with him long before the Stormont settlement.
Even without a formal assault on Mr Trimble's position, the opponents of a deal seem certain to act as a party within a party, denying Mr Trimble's authority.
It may be academic shortly because if, as expected, Mr Trimble stands for the assembly and becomes first minister he may resign his leadership of the parliamentary party.
Responding to the charge of a sell-out, Mr Trimble said: "My predecessor was called Judas Iscariot. For me to be called a traitor is very mild indeed."
He will, however, have drawn on the lessons of history, in particular 1974, when Brian Faulkner resigned the Ulster Unionist leadership after losing the backing of the party faithful. Yesterday, at any rate, Mr Trimble got the support that counts.