A judge-led review into the on-the-runs controversy cannot distract Stormont politicians from striving for agreement on the stalled Haass proposals, Martin McGuinness has insisted.
The deputy first minister said he remained optimistic that consensus on the blueprint for dealing with flags, parades and the legacy of the past outlined by former US diplomat Dr Richard Haass could be reached if politicians showed "leadership".
While the draft proposals emerging from Dr Haass's cross party talks process remain on the table since his chairmanship ended in December, efforts to strike a deal in his absence have made little progress and, arguably, have gone backwards.
One of the five parties involved - the Ulster Unionists - withdrew from negotiations in the wake of a political crisis triggered when details emerged about a deal Sinn Fein had struck with the Government that saw on-the-run (OTRs) republicans sent letters telling them they were not wanted by police.
Explaining his decision, UUP leader Mike Nesbitt accused Sinn Fein of "bad faith" in their handling of the issue.
The controversy developed when a case against a man accused of the IRA bombing of Hyde Park in 1982 collapsed because he was mistakenly sent one of the so-called assurance letters stating he was not wanted by the authorities.
Prime Minister David Cameron has ordered a judge-led review into the scheme - a two month process that will be led by Lady Justice Hallett.
Appearing at question time in the Assembly, Mr McGuinness acknowledged the OTR issue had been the subject of "much discussion".
"But I don't think it has necessarily harmed the (Haass) process," he said.
"I think the challenges that all the parties faced in relation to how we deal with the past, how we deal with the issue of parades and the whole issue of identity clearly showed in those discussions that there was a very large measure of agreement around the type of architecture and mechanisms that would be required to move us forward.
"I think that still represents the big challenge for all of us."
He added: "I think the big challenge for us, and certainly the scenario I would like to see, is whatever is happening in terms of whatever reviews are taking place over the OTRs that doesn't interrupt the essential work the party leaders have to engage in if we are to bring the Haass proposals to a successful conclusion."
The Sinn Fein veteran was heavily critical of Mr Nesbitt, whom he said was "swimming against the tide" of the views of most MLAs.
"I have to say he has turned out to be a major disappointment in this whole process and someone who has not contributed in a serious way to finding solutions to very serious problems," he said.
Later Mr Nesbitt responded, accusing Mr McGuinness of failing to answer questions about the process and instead launching a personal attack on him.
During question time, Mr McGuinness also claimed that his and First Minister Peter Robinson's St Patrick's trip to the US was set to deliver "substantial job announcements" in the coming weeks and months.