What odds on neither Brian Cowen nor Enda Kenny leading their respective parties into the next general election? If the two latest opinion polls are anything to go by, that is a very realistic possibility. Nothing may happen in the short term (although that is not guaranteed). Few in either Fianna Fáil or Fine Gael have the appetite for a heave against their leader although privately they accept that they cannot ignore indefinitely the increasingly clear signals coming from successive voter surveys.

The polls show that Fianna Fáil is heading for not just defeat but a drubbing that will see the party struggle to win in excess of 40 seats. Fine Gael is still heading for government but, 28 years after its last electoral victory, it is now facing the once unthinkable prospect of being eclipsed at the polls by a rampant Labour Party and being forced to play second fiddle in the coalition.

When The Irish Times polls of last June showed Labour overtaking both the big two parties for the first time, it was dismissed by Fine Gael handlers as a 'rogue poll'. But while there is better news for Fine Gael in today's Sunday Business Post, it's clear now that Labour is currently somewhere between the mid-20s and low-30s in terms of support and the prospect of it winning as many seats as Fine Gael cannot be ruled out. If that happens, then Eamon Gilmore can make a legitimate claim for a revolving taoiseach.

Publicly, the line coming from Fine Gael is that the leadership issue is over and that Kenny will lead the party into the next election. After the very public spilling of blood last June, there is an understandable reluctance to go there again. But it's hard to see TDs and senators, who have waited so long for their opportunity for government, sitting on their hands if polls continue to show Labour ahead.

The figures for Kenny in Thursday's TV3 poll were particularly stark. His satisfaction rating was a miserable six points ahead of Cowen at 24%, with half the electorate expressing dissatisfaction with his leadership. But even more worrying for Fine Gael TDs was the fact that only 45% of their party supporters were satisfied with Kenny and just 53% of them wanted him as taoiseach.

One Fine Gael TD, who opposed Kenny in June, said that the 53% figure was "astounding" and "had to be unprecedented" in Irish politics.

"Enda needs to do the right thing for Fine Gael and move aside... There won't be a heave. Either the men in grey suits call to him and he listens to them or he decides to do the right thing himself. He is now the Steve Staunton of Irish politics. He did a lot for the party in the past but he is not able to take the party on to the next level."

Another deputy said the poll bore out what he and his colleagues were getting in their constituencies. "Labour mightn't be at 35% but they're in the low 30s. It's what we hear; what we're being told on the ground and what we feel. They're a little bit ahead of us and they're learning quickly as regards getting candidates and so on. If they're close to 30% [in a general election], then they'll win 50 seats and be close to us."

A highly influential TD told the Sunday Tribune this weekend that he believed the Christmas period would be a determining time for Kenny's leadership.

"If the government gets the budget through then we could be looking at another eight months at least until a general election," he said. "The spin coming from the [Fine Gael] leadership is that an election is coming and to get the posters ready, but nobody really believes it. We might still be a year and a half away from the election [leaving time for a leadership move]. December could be crucial."

This was echoed by a Kenny-supporting TD who, when asked if Kenny would lead the party into the next election, replied: "If it is in the next two months, yes. If it isn't, I'd worry about him."

Another Kenny backer expressed frustration at the poll results. "What do people want from their politicians? We have worked to have policies on everything for going into government. So it is galling that Eamon Gilmore just tells the public what they want to hear. I am loyal to Enda but I also know that I am constantly asked about him by the public," the senator said.

But one senior figure who opposed Kenny last June believed it was now too close to an election to change. "We tried to get a new leader in June and that didn't work. I don't think that anyone wants to return to that situation. We have banged our head against a brick wall already and we don't want to return to that.

"The fact is that the situation with the government is so volatile that we are getting perilously close to an election. As we are so close to an election we cannot do anything about it."

However, others feel matters could come to a head quickly. They talk about "shock" within the party at TV3's poll result and a "dawning realisation" among those who had backed Kenny last June at what might be in store in a general election.

This may have abated after today's poll. And Kenny, it goes without saying after his marvellous rearguard defence three months ago, is not to be underestimated. He is a political street fighter and won't go easily.

But his rivals in the party believe that if the polls are more like the TV3 survey than the Sunday Business Post's, he will have to bow to the inevitable. They accept that there won't be another public heave, suggesting that if Kenny does go, "it will happen naturally". Despite being on the wrong side of last June's leadership battle, Richard Bruton is still seen as the obvious successor, with TDs saying he wasn't as damaged by that experience as might have been expected at the time.

There isn't any obvious successor to Brian Cowen in Fianna Fáil but there is a growing belief at all levels of the parliamentary party that, while nothing will happen in the short term, he will not be leader come the general election. While there was almost relief that, bad as they were, the poll results were not a good deal worse, one senior figure said: "There is a feeling beginning to grow that the Taoiseach will bring us up to the budget and... then if we get through that, early in the year, we will make a change."

He predicted that the leadership contest that followed would be an "east coast battle" with Brian Lenihan, Mary Hanafin and Dermot Ahern in the shake-up. While Lenihan'is the public's favourite, Micheál Martin is regarded by many as the frontrunner, his spell as health minister might tell against him, the source said, adding: "Watch Mary Hanafin. She's coming up on the rails and her election would be a game changer.

"She has managed not to be associated with the 2004 to 2007 mistakes even though her department [of Education] was one of the beneficiaries [of the rapidly increased spending]."

Hanafin's name has been mentioned by a number of Fianna Fáil TDs privately over the past fortnight. She is not universally loved in a parliamentary party that has traditionally put a high value on being 'one of the lads'. But they respect her media and communication skills. They are also far from unaware of the potential advantages of electing a first ever woman taoiseach.

Could it happen? In these extraordinary times anything could.