The British government must work to re-establish devolution in Northern Ireland, without Sinn Féin if necessary, the Alliance Party annual conference was told at the weekend.
Party leader David Ford denounced the Blair government over its record since Good Friday 1998. He also accused the British prime minister of acting contrary to the agreement itself.
Mr Ford called for a voluntary coalition at Stormont, the third party leader to do so, and accused the British government of punishing all the parties for the sins of republicans.
"A voluntary coalition, a Stormont coalition of the willing, is not about keeping people out," he said. "But about keeping things going."
In a series of attacks on Mr Blair, Mr Ford demanded action from Downing Street. "I have no apology to make for helping to bring Sinn Féin in to the talks process," he said.
"That was the right thing to do, following after the IRA ceasefire. In the agreement, it was realistic to accept that there could not be a transformation to a totally normal society overnight. But the function of a peace process is to bring peace, not to continue forever as an indefinite process."
He said it was past time for Mr Blair to tackle "the moral ambiguities" of his position and "long past the time the [ British] government stood by its call for acts of completion".
The conference also heard strong criticism of the new security powers granted to the British government last week. "Internment was wrong in 1971," said Mr Ford. "And it is wrong now."
Criticising all other parties as sectarian, he accused the UUP's David Trimble, the SDLP's Séamus Mallon and later Mark Durkan of operating a "sectarian carve-up".
"Community relations was seen as a problem for the interfaces," he said. Presumably if someone is too far away to lob a half brick at him you don't have any need to understand him or work with him to better society."
But it was the custodianship of the process by the British government that attracted Mr Ford's most scathing criticism. He said devolution was needed"on sensible terms" and "not with the crude mathematics of the d'Hondt formula to guarantee ministries to parties that refuse to co-operate".
He also attacked the designation system at Stormont whereby Assembly members must opt for a unionist or nationalist label."We need an Executive in which there is collective responsibility, implementing an agreed Programme for Government, working as a voluntary coalition." The governments were wrong to focus on "a quick fix" between Sinn Féin and the DUP and of pandering to their sectarianism.