A dramatic collapse of the Fianna Fáil-Green coalition was averted last night as the Green Party delegates voted overwhelmingly to endorse the revised programme for government negotiated by the two parties.

A second motion attempting to scupper Nama, which could also have resulted in the Greens' exit, fell far short of winning the required two-thirds majority, meaning the Nama legislation has now cleared its last major obstacle and is now certain to be ratified by the Oireachtas.

Despite fears in recent weeks that it would be a major struggle to secure a two-thirds majority for the new programme for government, when the result was announced just before 7pm last night, 523 delegates had voted in favour of the programme (84%) with just 99 (16%) voting against.

On the Nama motion, 32% of delegates voted to reject the bad bank proposal but this was less than half the number required to change party policy on the issue and Green TDs and senators are now free to support the legislation.

Party leader John Gormley welcomed the vote thanking members for their "overwhelming endorsement". He said his party would have to live up to those expectations and warned "this programme has to be implemented".

The result was an enormous relief for the Green leadership and for Taoiseach Brian Cowen. A failure to secure the two-thirds ratification would have resulted in the Greens having to withdraw from government, causing an inevitable general election in which both government parties faced massive seat losses.

Instead the coalition has now effectively cleared three of the four major hurdles it faced at the beginning of this Dáil session. Lisbon has been passed. The programme for government is agreed and Nama is now effectively done and dusted. However, government figures acknowledge that the biggest hurdle – a budget involving cutbacks of €3.75bn – still lies ahead in December.

However, last night's comprehensive vote does offer the under pressure government some respite. With hindsight, the outcome was scarcely in doubt once details of the new programme for government emerged, showing significant concessions for the Greens.The key measures for the Greens were:

* a commitment to tighten the rules on tax exiles

* a ruling out of third level fees

* no further increases in the pupil teacher ratio

* 500 new teaching positions

* an end to corporate political donations

* transparent appointments to state boards

* electoral and expenses reforms

* a phase out of fur farming in three years and an end to stag hunting.

However, significantly there was no definite commitment not to reduce social welfare rates, merely a promise to protect "the most vulnerable in society". Nor was there a specific pay cut for politicians included, although the report does commit to taking "further action" on pay rates.