A junior minister in the fledgling minority government is poised to vote against it on its first major challenge.
John Halligan, Minister of State for Training and Skills, said he thinks he will back Opposition demands in the Dail this week to scrap Irish Water.
The Fine Gael-led administration is planning to suspend water charges for nine months this summer pending the outcome of an independent review.
But 39 TDs opposed to the controversial levy are forcing a vote on its immediate abolition instead.
Mr Halligan, an Independent TD for Waterford who was appointed a junior minister last week, signalled he was going to back the motion on Wednesday.
“I don’t agree with [water charges], I haven’t paid them,” he told Today FM.
“If I am billed I won’t pay them and I think Irish Water is a failed entity, there is no question about that.
“I think I will be voting in favour of [the motion] because I don’t think it is fit for purpose.”
However, he added he has yet to see the wording of the motion and whether it clashes with the Programme for Government.
Fianna Fail has yet to indicate how it will vote on the motion, while Fine Gael has signalled it will put down a counter-motion it hopes will get enough backing to see off the challenge.
The anti-water charges motion was launched by Sinn Fein and Anti Austerity Alliance-People Before Profit TDs, with the backing of several Independents and the Social Democrats.
It also calls on the Government to set a date for a referendum on giving constitutional protection to the public ownership of water.
Sinn Fein’s Eoin O Broin said a majority of TDs elected in February’s general election were in favour of scrapping water charges.
“The overwhelming majority of people voted to scrap water charges and abolish Irish Water,” he said.
“We expect all the TDs elected on the anti-water charges platform to vote in favour of this motion.
“We also expect the Government to respect the democratic will of the people and to scrap this charge.”
A demonstration is also planned for outside Leinster House on the day of the debate.
Catherine Murphy, of the Social Democrats, said voters gave a very strong mandate on Irish Water in the general election.
“This motion reflects that mandate and as such, the Social Democrats are happy to support it,” she added.