SAMMY Wilson claims Sinn Féin is "not really committed" to the restoration of devolution and that "signs of stress" have already begun to appear in the restored institutions.
The DUP MP also takes a sideswipe at his own party leadership, accusing them along with the other parties of "foolishly" signing up to spending commitments which are not deliverable.
The former Stormont finance minister, who soon after the New Decade New Approach deal was signed told his successor Conor Murphy to stop complaining about the scale of the British government's financial package, said the return of devolution will "hopefully... bring political normality" to Northern Ireland, which he argues will be "good for the status quo and the union".
But the East Antrim MP claims that after initial relief that a deal – "however flawed" – had been reached, cracks have begun to appear and that the institutions could collapse.
"Sinn Féin are not really committed to the restoration of the assembly. After all there is no political benefit for them in making the institutions work: their long term aim of taking Northern Ireland out of the UK is not advanced by supporting the constitutional status quo," he writes.
"The first signs of trouble which could put the assembly in jeopardy emerged when Sinn Féin took on the role of finance minister. Immediately they started to complain that the government had reneged on promises about a huge fiscal windfall to accompany the devolution deal."
Writing a blog for centre-right think tank Politeia, Mr Wilson acknowledges that the British government promised "some money" to resolve the nurses' pay dispute and tackle the longer-term structural reforms needed in the health service and education.
"However, despite foolishly including in the deal a wish list of projects and spending commitments which were never deliverable even with the most generous of allocations of money (through the block grant from central government), none of the parties had sought assurances on the amount of money which would be allocated to the newly formed executive," he writes.
"Now the finance minister is calling foul and demanding the funding package be increased, but at a time when any negotiating leverage has gone."
The DUP MP says the secretary of state is unlikely to provide any more money because the SNP is "ready to seize upon every action they find by the government to justify their perpetual demand for another independence referendum".
