Richard Haass: Northern Ireland parties must justify decision
The chair of talks aimed at resolving parades, flags and the past has said the two unionist parties and Alliance have to justify their decisions not to fully endorse his proposed agreement.
Richard Haass said accepting the deal was not a close call.
He said implementing his proposals would help create a much calmer NI.
Sinn Féin and the SDLP have endorsed the proposals, but the DUP, UUP and Alliance have so far rejected elements of the Haass blueprint.
Speaking to the BBC's View programme from New York, Dr Haass said he hoped the British and Irish governments would continue to work with the parties, but the critical matter was for the Stormont parties to compromise.
"For the three parties that were not prepared to endorse it, they each had obvious concerns, some were articulated more than others," he said.
"I would prefer for them to speak and to justify or explain their choices about what it was that led them to think that they, narrowly, or the society as a whole, would be better off without this agreement."
The former US diplomat said the parties were going to have to "defend their positions".
"Why three in particular were not prepared to endorse this agreement that quite honestly, I and we feel, gave them more than enough to go out and defend it, not to just the general public but to their own particular constituencies," he said.
"The two unionist parties and the Alliance were not prepared to sign on to the agreement and I make it clear this was, if you will, collectively their agreement.
"This had been an agreement that all five parties worked on for six months and we had gone to enormous lengths to try to take into account their particular views, their concerns, their priorities and we thought we had done just that."
In response, Alliance Party MP Naomi Long said: "I think in our case his frustration is slightly misdirected since we have committed to implementing the process.
"When I went into the process with my colleagues, we said quite clearly we were not there to cook fudge.
"The proposals on flags are fudge to make other parties' refusal to deal with issues like flags more palatable. I won't be part of selling that to people.
"I will simply be honest and say unionists refused to deal with the unofficial flying of flags on lampposts; nationalists refused to compromise and deal with issues of official flags on buildings."
Dr Haass also said not reaching an agreement was unfair to victims and survivors of the Troubles and very bad for Northern Ireland.
He said he hoped a deal could still be reached and implemented, and said if there was, there would be benefits, with a calmer society requiring less expenditure on policing and enjoying increased investment and tourism.
Dr Haass, brought to Northern Ireland with Prof Meghan O'Sullivan in July by the first and deputy first ministers, to chair talks with the five main parties in an effort to resolve some of the most divisive issues that have hampered the Northern Ireland peace process.
The talks ended on New Year's Eve without agreement after parties received a seventh set of draft proposals.
On Monday, Dr Haass and Prof O'Sullivan published a two-page summary of their blueprint.
The DUP has said the final Haass proposals needed "much more work".
Party leader and Northern Ireland's First Minister Peter Robinson called for an "all-party working group" to be set up.
He said the aim of the working group would be to "resolve outstanding areas of disagreement and implement agreements when identified".
Ulster Unionist leader Mike Nesbitt said the proposals were "not viable or acceptable".
He said it was up to Mr Robinson and Deputy First Minister Martin McGuinness to "clear up the obvious mess created by this process".
The Alliance Party said it would support the proposal on the past, but has raised issues about suggested resolutions on flags and parades.
Sinn Féin's ruling party executive is due to meet on 11 January to consider the proposed agreement.
Like Sinn Féin, the SDLP have signalled a willingness to back Dr Haass's proposals.
Party leader Alasdair McDonnell said despite some concerns he anticipated his party would accept the agreement.