In the middle of an election campaign, it can be hard to see what statement or policy makes an undecided voter start to think about where they'll put their 'No 1' mark.
During the 2020 election, the surge in support for Sinn Féin came relatively late in the campaign, countering the traditional dynamic of government popularity during the electoral cycle.
"Increasingly voters are deciding later and later in the process," said Dr Kevin Cunningham, statistics lecturer in TU Dublin and founder of Ireland Thinks.
For the referendums on family and care which took place in March of this year, the election polls initially projected a 'Yes' vote for both.
"And then almost as late as a week out, the same polls showed that voters had switched radically towards a no position," Dr Cunningham said.
"Those that were most interested in voting no tended to be much more likely to be engaged in this topic and so there's an idea that those that are engaging with the politics might have an oversized influence on outcomes in their small social networks," he explained.
He said that when it comes to the growing number of 'late deciders' in Irish elections, there are five broad categories.
The first category is 'political learners'. These are younger voters who tend to decide late because they are still learning about the process of voting.
"They're learning principally about the political process when the election has happened. It's the first time they've been kind of forced to pay attention on the topic."
Next is the 'floating voter'.
"There are people who are just less interested in politics, and they'll wait until things are immediate before they decide who they're voting for.
"It's sometimes said that these voters actually vote quite randomly relative to the overall population, that there isn't any particular obvious pattern in their voting behaviour," Dr Cunningham said.
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The third category is the 'strategic voter'. In an Irish context this incorporates the types of people who are voting on the basis of government formation and the parties they would like to see form a government together after the election.
"What becomes much more apparent to voters during the campaign, is who is in government, who is not in government and what the choices are in respect to changing who is government or keeping who is government there."
Dr Cunningham explained that learning about this process influences how people vote too.
'Cross-pressured voters' have conflicting interests. "They might be loyal to one party but they certainly like a different party," he said. This voter is very hard to predict.
The final category of voter is the 'disaffected voter'. If this person does vote, they typically decide very late in the electoral campaign.
With so many undecided voters available, aspiring TDs use every medium possible to get their message across.
As the 15th General Election of his career approaches, political columnist with the Irish Times and former political editor, Stephen Collins, said that the obvious thing that has changed in that time is social media.
However, posters on lampposts and door-to-door canvassing are still the main ways to gain votes, he said.
"The old fundamentals still apply. In order to get their message across candidates have to meet as many people as possible.
"They have to hit as many people as possible with their message and there are new ways of doing that, but the old ways are still very important."
According to the RTÉ, Irish Times, TG4 and UCD exit poll after the 2020 election, just over half of the voters had made up with minds before the election campaign began.
"But during the campaign, the other half make up their minds and about one-quarter decide during the campaign and one-quarter say they only decide in the last day or two," Mr Collins said.
"So that means that the message being delivered by the parties is actually very, very important.
"More than half the people say they decide on national issues, but close to half say they decide on local issues.
"A lot of it is down to the individual," Mr Collins added.
Emphasis on voting for the individual TD, rather than the party they belong to, could impact the larger parties acutely, especially with so many sitting TDs not seeking re-election this time around
"There are a number of people stepping down, particularly in Fine Gael," Dr Cunningham said.
"The difference between Fine Gael and Fianna Fáil for voter has narrowed or disappeared.
"Many people who might have voted for a given Fine Gael candidate because they might have been loyal to that candidate might just as easily switch to a Fianna Fáil candidate."
Dr Cunningham said the same pattern is true for voters switching their preferences between Labour, Social Democrats and the Green Party.
At Dublin Zoo recently, potential voters spoke to RTÉ's Morning Ireland, and many said they had already decided who they are going to vote for in the next election.
"My TD is retiring, so I'm going to vote for the person who's gonna replace him," one voter said. She added she would be loyal to the individual candidate rather than a particular party.
Another voter said that he sticks with the same people most of the time. "The opposition just wouldn't suit my viewpoints at all," he said, adding for him climate change is the main issue he wants the next government to address.
One woman said that while she had been leaning towards Sinn Féin, she has changed her mind. "Maybe more independents," she said, adding that women's health was her biggest issue.
Another woman said that she thinks she'd be voting for someone different if she was younger but now she's going to vote "for somebody who'll look after families like ourselves with childcare - it's a big issue in our house."
While another person didn't know who'd she'd vote for at the moment, the big issue she wants addressed is housing.
"I'm just listening to everything that's going on and I'll decide then," she said.
"I would have said I used to vote for the same party because it was what my dad did, and he was a staunch Fine Gael man.
"I tend now to vote for the person who does the most. For my myself, my family and the community, and that's basically what I vote for now."
