Sinn Féin leader Mary Lou McDonald is to be invited to take part in a televised election debate with Taoiseach Leo Varadkar and Fianna Fáil leader Micheal Martin.
RTÉ has reversed its decision to exclude Ms McDonald from the TV debate after a rise in Sinn Féin’s popularity in recent opinion polls.
Ms McDonald said she is "pleased to accept invitation to tomorrow night's leaders' debate on RTÉ."
A poll this weekend showed Fianna Fáil and Sinn Fein level on support while Fine Gael was trailing behind them.
The broadcaster is also planning to hold an additional five-way debate featuring the leaders of the smaller parties.
This will include the Labour Party, Green Party, Social Democrats, Solidarity-People Before Profit and Aontú.
In a statement, RTÉ confirmed Ms McDonald will appear on the originally planned Prime Time Leaders Debate which is due to air on Tuesday evening. It also said the five other leaders will be invited to take part in a new debate on Thursday.
RTÉ noted the Broadcasting Authority of Ireland’s (BAI) rules for covering elections which states that broadcasters should give “active consideration” to their coverage and “amend this approach if they consider it necessary and appropriate so as to ensure fairness, objectivity and impartiality”.
RTÉ said the station “is very mindful” that it has a duty to the public to reflect events as they unfold.
“During the course of the campaign and over recent days RTÉ has taken into consideration the notable change in the dynamic of the campaign on the ground, and representation and statements by political parties. The dynamic has also been consistently reflected in all opinion polls since the campaign commenced,” it said.
“We now consider it necessary to amend our original approach, respond to the changes in the campaign, and continue to put the audience first in the making of Tuesday night's programme,” it added.
Sinn Féin director of elections Pearse Doherty welcomed the u-turn by RTE but said it should not have “come down to a last minute decision.”
"Fine Gael and Fianna Fáil wanted this election to be about them, but this election was never about two parties with no real policy differences, who have effectively been in government together for the last four years,” he said
“Neither of them represent change. Sinn Féin are the real voice of change in this election and are the only party that is committed to giving workers and families a break,” he added.
Taoiseach Leo Varadkar said he welcomes Ms McDonald's inclusion in the debate as it will be a chance to scrutinise Sinn Féin's policies.
He said that in their manifesto Sinn Féin are promising no carbon tax, no property tax, reducing the USC for many people and no college fees.
Mr Varadkar said that under Sinn Féin's plans all of this would be paid for by "massive taxes on business" and argued: "That ain't gonna work."
He said: "It might work for a year or two, but if you impose that much tax on business, on jobs, on pension pots, on wealth, what happens after a few years is that the businesses close the jobs are lost. Investment goes to other countries, wealth leaves and we lose the battle for talent.
"And then you end up short on money and it's the poorest people who always suffer when that happens.
"So it will be a chance I think to expose some of those policies," he said adding: "They didn't work in East Germany, they didn't work in Venezuela. They're certainly not going to work in Ireland."