Micheál Martin has said unionism should have “claimed victory” on the Windsor Framework.
The Tánaiste also told the BBC that the majority of what the DUP was trying to achieve was awarded in the Framework.
The devolved government in Northern Ireland has not been operational for over a year due to the DUP’s boycott of power-sharing institutions in protest against post-Brexit trading arrangements.
Unionist parties including the DUP expressed concern that the initial post-Brexit trade deal, the Protocol, created a border in the Irish Sea by implementing checks on good travelling between Northern Ireland and mainland UK.
The Windsor Framework, introduced by British Prime Minister Rishi Sunak, sought to alleviate these concerns through the creation of a red lane, green lane system to minimise checks on goods coming from mainland UK to Northern Ireland not intended for further travel into the EU.
The DUP declined to return to government following the Windsor Framework announcement and is currently in negotiations with the British government to seek further legislative assurances of Northern Ireland’s trading position within the UK.
Mr Martin said the DUP leader Jeffrey Donaldson wanted to return to government, but should have done so after the Windsor Framework was announced.
“I take in good faith Jeffrey Donaldson’s commitment that he wants the executive and the assembly back,” he said.
“I think the Windsor agreement was a major milestone, I think actually unionism should have claimed victory on the Windsor agreement.
“Much of what they campaigned for, the vast majority of what they campaigned for was delivered in the Windsor agreement.”
Asked if he believed it was a mistake by Mr Donaldson not to endorse the Windsor Framework, Mr Martin said “I do”.
“I think it was a missed opportunity because things were provided for in the Windsor agreement that unionism was told couldn’t be provided for two years ago,” he said.
During a visit to Belfast in August, Taoiseach Leo Varadkar said if Stormont was not operational by autumn that it would be time to consider alternatives or “plan-B”.
Mr Martin said that the Irish government would work with Northern Ireland parties and the British government in exploring “next steps”.
“There is no specific plan B there and I think the use of the phrase plan B is not the most elegant of phrases to characterise this,” he said.
“But let’s be clear that if the institutions aren’t back, that is fairly fundamental in terms of the Good Friday Agreement, and I think it will mean that the British and Irish governments will have to engage, and with the parties involved, in terms of next steps.”
