The Government could "discard" the Green Party at any time, according to its leader, John Gormley.
He also said Mr Ahern had not interfered in the work of the two Green Party Cabinet members and he added that it was Mr Ahern who insisted the Greens should be in Government.
Mr Gormley was speaking during an interview on RTÉ's The Week in Politics.
He said the Taoiseach "has taken on board the issues we're interested in" and the relationship was a constructive one.
"So far I have to say, there has been no interference. He has said to us 'get on with the business'. He is interested in people doing work. We are working very hard," he said.
When interviewer Seán O'Rourke suggested Green issues were a "political fashion accessory" that could be discarded, he replied: "You're quite right. They could discard us at any stage if they were so inclined." But he said they could also discard the PDs or the Independents.
Mr Gormley said he believed the Taoiseach's priorities had changed before the Green Party entered Government.
"It's very clear to me that he was the one who insisted that the Greens should be part of the next government" and Mr Ahern "understands that climate change is the biggest issue facing humanity".
Asked if he was keen for Mr Ahern to remain as Taoiseach because others might not be as sympathetic to the Green agenda, Mr Gormley said he had a good relationship with the Taoiseach.
"I would be happy with Brian Cowen at the helm, or indeed there are other people at the Cabinet table who would do an equally good job, " said Mr Gormley.
Earlier, the party's chairman, Dan Boyle, said what the Greens achieved in Government was "going to be proportionate. We're not the tail that wags any dog".
