Martin McGuinness' claims that Peter Robinson is "dancing to the tune of loyalist extremists" is a smokescreen to hide Sinn Fein's leadership problems, the DUP has claimed.
Nigel Dodds said the Deputy First Minister's "insults" were just the latest in a long list of attempts by Sinn Fein to distract from its own internal difficulties as its politicians jockey for position to replace Gerry Adams.
The war of words erupted after Mr McGuinness let fly in a hard-hitting interview with the Irish News, which set the scene for the start of Sinn Fein's annual conference in Wexford today.
A clearly frustrated Mr McGuinness said he was "embarrassed by the image of the Executive" and found it difficult to work with his DUP partners in Government. He claimed that, after two years of sharing power, three-quarters of DUP MLAs won't even acknowledge him when they pass in the corridors.
"Quite clearly an instruction has been issued to some DUP members not to be seen to be too close to Sinn Fein," he stated, before accusing Peter Robinson, the DUP leader and his political partner, of "dancing to the tune of loyalist extremists".
He cited issues like the planned peace centre at the Maze, which he said Mr Robinson cancelled without any consultation, as well as flags and parading.
He pledged that he would still push ahead with the Maze centre despite the DUP veto, but he didn't explain how this would happen.
After Mr McGuinness' onslaught, the DUP struck back in equally strident terms, accusing Sinn Fein of attempting to mask its own difficulties.
"Some may feign surprise at the comments from Martin McGuinness but they are the latest attempt by Sinn Fein to throw insults as a crude distraction from the leadership jockeying within the party's own ranks," said DUP deputy leader Mr Dodds.
"No one in the DUP will take any lectures from Sinn Fein about responding to violence.
"Unlike Martin McGuinness, Peter Robinson has always stood against terrorism. The DUP has always condemned all terrorism and violence whenever or wherever it occurred.
"I look forward to Martin McGuinness condemning, not just the violence of today, but the violence of the past also.
"Sinn Fein's problem is not that they can't reach agreements with unionists, but they can't take a decision within their own party."
Another DUP source dismissed Mr McGuinness' concerns as the effect of internal Sinn Fein politics.
"He can't tell you the time of day without consulting some politburo," one said.
Despite the fraught relations between the two largest parties and Mr McGuinness' outspoken criticism of the DUP, Sinn Fein dismissed any notion that it could pull out of Government.
"We have devoted too much time and effort over 20 years to bring this process to this point to walk away now," a senior party source said.
"We are here because nationalists and republicans have elected us to be there. It is part of an overall strategy to deliver Irish unification."