Unionists who claim there is "no alternative" to the Belfast Agreement are "doing a disservice to their own community", the president of the Ulster Unionist Party, the Rev Martin Smyth, has said.
In a stinging rebuke to his party leader Mr David Trimble, the Rev Smyth, one of three UUP MPs who resigned the party whip at Westminster last month, said "there is no politician worth his salt who would say 'there is no alternative'."
The "minority of unionists" who supported the Belfast Agreement should instead be "striving to work with fellow unionists to achieve arrangements which could command widespread unionist support and resolve unionist concerns", he said.
"One of the offences levied against me has been my intention to work with other unionists towards some semblance of broad unionist unity. When others have talked to, and sought to work with, other parties, including Sinn Féin and the SDLP, why is there a problem in having discussions with other unionists?
"Once the summer is through I expect there to be some progress towards that happening."
The MP for South Belfast was addressing a Twelfth demonstration at Crossgar, Co Down, attended by up to 5,000 Orangemen and 20,000 supporters on Saturday.
Only a few hundred, however, gathered to listen to the speeches, which came at the end of a three-hour parade, with the vast majority of marchers intent on enjoying refreshments in the sunshine instead.
In keeping with tradition, the Orangemen passed motions of loyalty to Protestantism and the British Crown.
Proposing the Orange Order's third resolution at the rally, namely that dealing with loyalty to the unity of the British state, Mr Smyth - a former Grand Master of the Order - cited a difference between "anti-Belfast Agreement" and "anti-any agreement".
"Unionism can support an agreement but the Belfast Agreement will not survive without unionist support."
He received approval from the crowd when he spoke of the "not unreasonable" opposition to working with people who remained armed and continued with "operations of terrorism".
Referring to a remark by the Taoiseach, Mr Ahern, before the Republic's last general election, "that those linked to that continuing terrorism should not have the right to govern", Mr Smyth said: "If it's good for Bertie in Dublin, it's good for us in Belfast."
The MP claimed he was speaking for hundreds of thousands of "ordinary and sensible unionists" whose opinion was being ignored.
Referring to the disappearance of Gareth O'Connor from south Armagh two months ago, which is being linked to the IRA, he remarked: "Such people cannot be tolerated in government We can no longer tolerate gunmen and their supporters in power in the Assembly."
The Belfast Agreement had "institutionalised gangsterism and violence", he said.
But those who criticised it had "been demonised more than the terrorists, all for holding a legitimate and democratic point of view. Some of us have been described as 'rebels', 'dissidents' and 'hardliners'. How can one be a rebel and a dissident when one has consistently maintained the same values and principles all along," he asked.
"In the long term, no agreement will survive without the consent and approval of the unionist community, as well as the nationalist community.
"The illogical cry of 'no alternative' ignores the fact that governments and the parties would have to face the reality if a majority of citizens, either unionist or nationalist, refused to work the current arrangements."
In a prayer service earlier, district lay-chaplain Mr Robin Fairbairn urged those present not to be ashamed of their past or the faith of their forefathers.
The prayers and resolutions came at the end of a lightly policed demonstration.