THE leaders of the two main political parties are under intense pressure this weekend following Friday's extraordinary opinion poll, with the future of Fine Gael's Enda Kenny, in particular, in the balance.

Taoiseach Brian Cowen will survive Tuesday's confidence motion, but he has been badly damaged by last week's banking reports and there is "huge unease" within Fianna Fáil at the latest collapse in party support.

While the confidence motion has ensured there will be no imminent challenge to Cowen from within his own party, Enda Kenny is facing into arguably the most important week of his leadership of Fine Gael.

His parliamentary party is in shock after The Irish Times Ipsos MRBI poll showed Fine Gael being overtaken by the Labour party. Senior party figures said this weekend that Kenny's chances of survival are now "50-50 or worse".

One senior TD told the Sunday Tribune yesterday that deputy leader Richard Bruton is "key" to what happens next. "If Richard says 'I want the leadership', then the majority of the front bench would back him," he said, adding that there was a lot of pressure coming on Bruton to make a move.

The finance spokesman could not be contacted yesterday, but he pointedly failed to declare his confidence in Kenny on at least two occasions on RTÉ's Prime Time programme last Thursday night. "Everybody is talking about it in the party," one TD said.

Kenny retains considerable support among older deputies, particularly in rural areas and commands huge respect across the parliamentary party for his role in rescuing Fine Gael from oblivion in 2002. "Don't underestimate Enda. He has possession and he's a very good political animal," one senior figure said.

One key figure, Leo Varadkar, has publicly backed Kenny. The Mayoman's closest political ally on the front bench, Phil Hogan, told the Sunday Tribune yesterday he had "been speaking to a lot of people in the party over the last 24 hours and nobody is of the view that the leader of the party should be changed.

"People have learned lessons from the past and we should not be having an internal discussion about our leader when we are on the verge of a general election. Enda will lead the party into the next general election and election results should be the only results by which leaders are judged," he said.

However, it is clear that there are other TDs who privately want Bruton to take over. There was irritation at an email from the leadership on Friday pushing the line that this was "a rogue poll" with many feeling for some time that the party has been stuck in neutral.

Senior figures believe that the issue should be sorted by the front bench and shouldn't "be left to the malcontents". They are at pains to avoid a "bloodbath" – memories remain fresh of the previous bitter leadership battles 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," said one TD.

Others in the party, though, are determined 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," another TD said.

But this was discounted by a senior deputy who said: "If Richard doesn't go for it, then it won't come to a head". He added that "one way or another", the issue would be decided in the coming week.

If Kenny was to be ousted, it would inevitably increase the pressure on Brian Cowen, with one senior Fianna Fáil figure admitting "if there's a new leader in Fine Gael, that changes the ball game. That's a whole different scenario."

There is now a sizeable rump of more than two dozen TDs within Fianna Fáil who are unhappy with Cowen's leadership. However, he is being saved from a challenge by the absence of a senior figure opposing him and the fear that a successful heave would cause a general election. "Who's going to want to take it over now? And if we were to have a second unelected taoiseach, it would precipitate a general election and nobody in the party wants that," one long-time TD said.

However, there is an alternative view that Cowen has been so damaged that the issue will have to be confronted.