Anti-water charge campaigners are banking on 100,000 people taking to nationwide protests on Saturday.
At least 30 demonstrations have been organised in towns and cities up and down the country as part of the sixth day of action by the Right2Water movement.
Spokesman Brendan Ogle said big protests are expected in Cork and Letterkenny and the largest will be in Dublin where about 20,000 people are predicted to take to the streets and rally at the GPO.
"We'd be very happy with that. We are looking at 100,000 around the country," he said.
"If we get into six figures it'd be amazing."
Among the protests, campaigners will picket the Fine Gael ard fheis in Citywest at noon.
Right2Water, backed by trade unions including Mandate, Unite, the Communication Workers' Union, power union the TEEU, and the Civil and Public Services Union, plans to follow the latest rallies with another major demonstration on the Saturday before the election day.
It also plans a high profile conference with a panel of international speakers at the height of the election campaign.
Mr Ogle added: "The one before the election would be the biggest there's ever been.
"If politicians are saying they are not hearing this issue on the doorsteps then I don't know what doorsteps they are on."
Right2Water's latest campaign centres on claims that households use 10% of water produced in the country compared with big business and agriculture but they pay nearly 80% of costs.
It also attacked Irish Water figures which found 61% of customers have paid a bill.
Right2Water claimed Irish Water should have taken in 225 million euro in charges to date but has only collected 110 million euro and it has spent 80 million euro on conservation grants.
Paul Murphy, Anti Austerity Alliance TD, said: "People should turn out in large numbers for the national day of protest tomorrow to send a message to the Government parties that their latest concessions won't work, that this will be a major election issue and we want water charges scrapped."
At the last major rally last August, tens of thousands of people took to the streets of Dublin with organisers estimating 80,000 people marched and gardai putting the number significantly lower.