The Taoiseach Leo Varadkar has insisted that it is still "all to play for" in next week's General Election.
His comments come as a new opinion poll shows that Fine Gael has dropped to third place, commanding support from 21% of voters.
The Business Post/Red C survey of 1,000 people revealed that Sinn Féin and Fianna Fáil are neck and neck on 24% apiece.
Speaking on the BBC's Andrew Marr show this morning, Mr Varadkar said his party can still make up some ground.
He also reiterated his refusal to form a potential government with Sinn Féin following next Saturday's vote.
He said: "It's looking like a very tight election.
"We're a bit behind, but everything is within the margin of error of 3%, so this election is all to play for.
"One thing that won't happen, you won't see a coalition involving my party and Sinn Féin. That's just not going to happen.
"Sinn Féin, in our view, is soft on crime and also high on tax - proposals to tax business, pensions, incomes, wealth, property, you name it, to the tune of four billion euro and that would be enormously damaging for the Irish economy, for people's jobs and incomes and livelihoods and businesses.
He added: "The likelihood is it's actually going to be quite difficult to form a government in the next couple of months."
In the same interview, Mr Varadkar said that Britain should not set "rigid red lines" when attempting to establish a post-Brexit trade deal with the EU.
'A momentum for Sinn Féin'
Meanwhile, Sinn Féin leader Mary Lou McDonald said the new opinion poll shows the public's appetite for change ahead of Saturday's vote.
Ms McDonald said that she was taking nothing for granted and the party would campaign until the last minute.
She said: "Obviously it is reflective of an energy and a momentum for Sinn Féin and for change.
"We will continue to campaign until the last day and the last hour because we take nothing for granted.
"I really want, as we begin the final week of the campaign, to encourage people to use their vote because every single vote is equal."
Ms McDonald then gave her opinion on what would be a favourable and unfavourable outcome for her party following the election.
She said: "We have no intention of propping up bad government; for us the best possible outcome of this election is a government without Fianna Fáil or Fine Gael.
"The worst outcome for us is a government again of Fianna Fáil or Fine Gael working together.
"I'm not going to presume anything until the people have had their say, not one vote has been cast and I think it would be the height of presumption to start ruling in or ruling out ministries or individuals."
Martin 'satisfied' with Fianna Fáil's position
Micheál Martin said he believes his party will outperform today's poll in the upcoming election.
Despite the drop in support for Fianna Fáil suggested in the poll, Mr Martin said he was happy with the party's position.
He said: "I think we're concentrating on our poll, and we're quite satisfied where we are in terms of leading into the campaign and taking into consideration that we have much stronger teams on the ground than we had in 2016.
"I think we outperformed that particular poll this morning, because of the strength of our candidates on the ground and I think we're in quite a strong position to gain seats."
