DUP leader Ian Paisley is unlikely to attend a meeting alongside Sinn Fein leader Gerry Adams in a row over the ministerial pledge of office.
The meeting between the party leaders is not likely to go ahead
Mr Paisley and SF's Martin McGuinness are due to become shadow first and deputy first ministers on 24 November.
But the DUP is insisting that a pledge of support for policing and for law and order is in place before then.
It was seen as significant that Mr Paisley and Mr Adams were to sit at the same round table for talks at Stormont.
Both the DUP and Sinn Fein were meant to be represented at a leadership level at the new Programme for Government Committee at Stormont on Tuesday.
The committee is trying to agree priorities for the executive scheduled to take power next March.
However, Mr Paisley is accusing the government of backtracking on assurances over the pledge ministers must swear before taking office.
BBC Northern Ireland political editor Mark Devenport said: "The DUP want Martin McGuinness to swear to support law and order and the PSNI when he is nominated as deputy first minister on November 24th.
"But republicans are resisting that, not least because that will be before they hold a special party conference to decide their policing policy.
"Both sides are meeting the secretary of state today to discuss the matter, but the DUP says, as things stand, Ian Paisley is unlikely to attend this afternoon's committee meeting."
Sinn Fein leader Gerry Adams said he understood the DUP would be at the meeting.
"There may be technical games going on, and all of those difficulties which sometimes affect politics, but let's go forward if we can," he said.
"One thing is certain, what people are united about, whatever about the detail, is that they want a better future for our young people."
Sean Farren, of the SDLP, said the DUP should not be relying on private assurances.
"Let's not get carried away by what the DUP are claiming were promises, commitments, assurances made to them by anybody.
"The history of this process shows that such assurances...frequently turn to dust."
Last week's St Andrews Agreement stated that before the government legislated on the pledge of office, "it will consider the outcome of further Preparation for Government Committee discussions on policing and the rule of law".
Mr Paisley's son, DUP assemblyman Ian Paisley Jr, warned the government "would have a lot to answer for" if the pledge issue was not resolved.
"If there's not delivery, I do not believe today's meeting will be attended by Dr Paisley," he said.
Meanwhile, DUP MEP Jim Allister expressed concern that the IRA is not obliged to disband its army council under the St Andrews Agreement.
Mr Allister stressed he was not rejecting the package, but wanted to see healthy debate within the party.
"We cannot go into government with Sinn Fein in a situation where the party still has an army council at its beck and call and where there is a lack of delivery through the courts for convictions by allowing people to give evidence," he said.
The Northern Ireland parties have been given until 10 November to respond to what the governments are calling the St Andrews Agreement.
It was published after intensive three-day talks between the parties at St Andrews in Scotland.
If all goes to plan, a first and deputy first minister will be nominated on 24 November and the devolved institutions will be up and running by 26 March.