Published Wednesday, 18 September 2013
However, the DUP leader has said Dr Haass can make progress on the three contentious issues.
The diplomat started work on Tuesday with his vice chair Meghan O'Sullivan, who both have experience of local issues and of building relationships in post-conflict societies.
The former US special envoy is holding discussions with the political parties and other interested groups on how to tackle issues which have created division.
On Wednesday Dr Haass met with the DUP and UUP as well as various other groups.
After the meeting, Mr Robinson accepted that the December deadline for resolution would be difficult to meet but claimed significant progress could be made.
Speaking outside the Stormont Hotel flanked by Orange Order chaplain Reverend Mervyn Gibson, Lagan Valley MP Jeffrey Donaldson and Stormont Junior Minister Jonathan Bell, he said: "Do I believe we will be able to have all of these issues cut and dried and resolved by Christmas? No, I don't.
Do I believe that there can be progress on each of them and some more than others? Yes, I do.
The DUP delegation met with Dr Haass for over an hour during the second day of negotiations.
Outlining the DUP's position, Mr Robinson said they were "determined to contribute in a positive manner" but noted they had their own "very distinct angle of vision" on the three contentious issues.
He said: "We believe that there are certain freedoms that need to be enshrined and protected.
"One of those clearly is the ability for people to assemble and to parade and we have obviously indicated how important that is to our community - that it is part of the unionist, loyalist, Protestant culture in Northern Ireland.
We have touched on the issue of flags and made it very clear that for us a shared future is not a neutral environment - it is a shared future within the United Kingdom.
"Northern Ireland constitutionally is part of the United Kingdom, the Union flag is the flag of our country and should be respected," he said.
"We have dealt with the issues of the past and how difficult it would be to get a common narrative.
"But we have indicated some areas where we think progress could be made."
Mr Robinson also acknowledged there would be challenges ahead.
"November and December will be the tough months when we have to get down to the real work."
The ex-White House special envoy also held separate discussions with the UUP, members of the Royal Black Perceptory..
They both described the talks as "constructive".
Dr Haass later met with a delegation from the Alliance Party and a delegation representing the Presbyterian Church.
On Tuesday he met with Sinn Féin and the SDLP, telling reporters that while there had seen "tremendous progress" in Northern Ireland, the summer's violence served as a warning against complacency.
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