ON Tuesday Enda Kenny will be the chief prosecutor in the no-confidence motion against the Taoiseach, but it may be his own job, rather than Brian Cowen's, that is on the line.

Friday's Irish Times opinion poll was disastrous for the government but it was arguably even more shocking for Fine Gael.

Fianna Fáil is heading for the opposition benches after the next general election and has been for the past 20 months or so. Such is the government's unpopularity that nobody is too surprised to see the party's ratings down at below 20%.

But for Fine Gael to have only the same level of support it had in the 2007 general election – despite all that has happened, including a 25- point drop in support for Fianna Fáil – is galling for party figures. To make matters worse, Kenny's personal rating at 24% is only six points ahead of the beleaguered Cowen.

For the leader of an opposition party, opposing the most unpopular Taoiseach and government ever, the poll result cannot be explained away.

Rightly or wrongly, fairly or unfairly, the swing voters have looked at Kenny and Fine Gael on the one hand and Gilmore and Labour on the other, and moved en bloc to the latter.

Some of that is certainly down to Labour's nakedly populist approach. Fine Gael has certainly opposed much of what the government has done in cutting spending and bailing out the banks, but it has tried to be more constructive and hasn't shied away from spelling out that tough decisions have to be made.

In contrast, Labour has borrowed straight from the old Fianna Fáil opposition rule book: oppose everything; indulge every interest group; keep everyone sweet. It has gone down a treat with an angry electorate.

But the electorate's views of Kenny and Gilmore are also a major factor in the positions of the two parties. Gilmore has expertly, almost effortlessly, tapped into the public mood.

Kenny has not been able to do that. Based on the Irish Times poll, the electorate wants Fianna Fáil out of office but remain entirely unconvinced that Kenny is a viable alternative.

Even before Friday's poll, sources say there was growing discontent within Fine Gael about Kenny's leadership.

Last February, moves were afoot within the parliamentary party to get him to stand aside but they were stymied when George Lee resigned. Those involved in the plan didn't want to create the perception that they were acting on foot of Lee's resignation, so they backed off.

Kenny responded by upping his game – promising that the real Enda Kenny would emerge – and began a round of head-to-head meetings with individual members of the parliamentary party.

But despite the affection for the Mayoman, and the gratitude towards him for rescuing the party from the abyss of 2002, senior sources say the feeling has been growing in recent weeks that Fine Gael is stuck in neutral and might even be slipping back. They claim this was borne out by private constituency polls which showed the party simply holding its own.

The latest poll has now brought matters to a head and, according to TDs, made a challenge inevitable. There is widespread agreement that nothing will happen ahead of the confidence motion, but that moves could be made after that.

Expectations that something would happen were heightened by deputy leader Richard Bruton's repeated refusal to express confidence in Kenny on RTE's Prime Time on Thursday night.

Bruton was asked at least twice by Miriam O'Callaghan if he had faith in Kenny's leadership and he pointedly did not answer the question, preferring to focus on how "we're all in the dock". The fact that no front bench mem­ber was on Morning Ireland the following morning was also seen as significant by many in the party.

The almost universal view in Fine Gael is that, if Bruton moves against Kenny, it is all over. Bruton, who has an old-fashioned loyalty to the party leader, has refused to take action in the past. But there is a belief now in the parliamentary party that "Richard has to step up to the plate", and that he will.

Senior figures on the front bench are at pains to avoid a bloodbath – memories remain fresh of the bitter leadership battles of the post-FitzGerald era and the damage they did to the party.

"The last thing we want is a heave. We want to have a seamless transfer of power. It's not about a heave, it's about Enda realising himself where he is in the polls. There will be no leadership contest. Richard Bruton will be the next leader."

However, others in the party say that, if needs be, there will be a heave. "Ideally, it would be Richard stepping forward [and taking over without a contest] but if it's not Richard it will be somebody else," one party figure told the Sunday Tribune this weekend.

Kenny still has his supporters in the party, particularly along the western seaboard and among the Fine Gael old guard.

And he is a formidable political strategist who will not be pushed without a fight. While some TDs believe it is now a matter of when, not if, Kenny goes, others counsel that he is not to be underestimated.

But more neutral close observers take the view that "Kenny is going to have a job surviving". It's clear, as one source puts it, "there is a lot of activity behind the scenes".

Even those who want Kenny to go have mixed feelings about the moves against him. "It would be a personal tragedy for him. He has brought the party so far," one senior party figure said.

However, politics is a ruthless business. Fine Gael has waited nearly 30 years for a general election victory and the feeling is that nothing can be allowed to get in the way of that.

It shows how dramatically politics have changed, that it is no longer enough for Fine Gael to be ahead of Fianna Fáil. "We all know Fianna Fáil will not be in government after the next election. It's now a competition between the opposition parties," one senior TD said this weekend.

The problem for Kenny is that, of the 25 points Fianna Fáil has lost in the polls since the last general election, Labour has picked up 22 of them, while Fine Gael, as of now, is stuck where it was in 2007. That isn't sustainable. Something or somebody is going to have to give.