Mary Coughlan's unfortunate slip of the teanga may have Freudian depths. You don't have to be as clever as Darwin – or even Einstein for that matter – to know (having studied Irish compulsorily for 14 years) that glasraí, or vegetables, are not members of the Green party.

But you do have to possess a well-developed sense of superiority and condescension towards your junior partners in government to believe that they're green enough to allow themselves to be sidelined over the most important piece of economic legislation in the history of the country.

If reports are to be believed, there were "serious tensions" between Green party ministers John Gormley and Eamon Ryan and the Taoiseach Brian Cowen before the cabinet met last Wednesday over the details of the minister for finance Brian Lenihan's Nama speech.

The Greens were unhappy that their input into the Nama legislation, especially over the level of risk sharing between the banks and the taxpayer, and the need for a "social dividend", was not spelled out clearly enough.

And true enough, both Enda Kenny and Eamon Gilmore scented weakness, pouring scorn on the Greens and leaving John Gormley having to re-stake his credibility among his members and the wider public.

Whatever about the Greens wanting it both ways – to be at the centre of power but perceived by the public as a principled opposition – unless Fianna Fáil really does want to collapse the coalition it would do better to show some respect, especially when they are bailing out the banks with a loan of €54bn.

This government will fall unless the Greens can sell their renegotiated programme for government, which includes Nama, to its convention in the second week of October.

It is a pity therefore that the impression of a well-bonded government in which the senior partner valued the political instincts of its junior partner to give it a legislative profile has been so easily shattered.

Fianna Fáil should remember that, when the Nama legislation was initially published over two weeks ago, it took the intervention of John Gormley and Eamon Ryan to calm the public debate which was becoming hysterical and out of control. They managed to restore a level of sanity that got the wider public thinking that, maybe with some changes, Nama could become "the least worst" option. With the polls showing Lisbon still looking positive, but slightly less so, it was important that the public were persuaded to see the sense of Nama so that a drift by the angry brigade to the No side could be circumvented.

Ryan's insistence that there would be risk sharing, that taxpayers would get greater protection, and that banking reform, planning reform, accountability of board directors and a tax on rezoned speculative land would all be sewn into the legislation made it palatable to a far greater proportion of the public who, until then, felt the banks were getting it all their own way.

That the Greens could claim some credit for a Nama with a social dividend would seem a small price to pay. But in the end, the Greens have clearly been disappointed and embarrassed in front of their members. Gormley and Ryan now stand charged with overselling and exaggerating the safeguards they "won".

The result is that the Greens now go into talks about renegotiating the programme for government and the public spending cuts planned for the budget – all €3bn of them – in distinctly grumpy form. John Gormley has said that if the Greens' convention does not get the necessary two-thirds majority for Nama and the renegotiated coalition programme for government, then his party will walk. The failure to give a Green input into Nama in the Dáil on the day it would be stitched into the history books has made that scenario all the more likely.

The irony is that the vast majority of the public were on the Greens' side over the need for a social dividend from the toxic debt legislation. The government as a whole would have benefited from it.

The debate is moving on now to the budget and the distinct possibility of public sector pay cuts and unthinkable social welfare cuts.

They will trigger public protest unseen for a generation. Nama had to dish out some retribution to reckless bankers, as set out by the Greens, if even a proportion of the public was to be persuaded that the government is moving in the right direction.

But all the public sees now is share prices going up and bankers looking sheepishly triumphant.

Hail Eamon Gilmore's "toxic triangle" of Fianna Fáil, the developers and the bankers.

The social dividend should have made the headlines, even as window-dressing for Nama. The Greens saw that and Fianna Fáil should have too. Failing to green Nama was a lost opportunity – for all the financial acrobatics displayed by the finance minister and his advisors, there's a real question over who are the political glasraí now.