The Minister for Foreign Affairs has said the backstop agreement on the Irish border has been turned into a "green and orange" issue.
Simon Coveney also said getting a good deal for Ireland in the Brexit talks is being hampered by the actions of political parties.
Mr Coveney said that Ireland cannot allow one political party in Northern Ireland - the DUP - to veto proposals on the backstop agreement.
Speaking on RTÉ's Marian Finucane programme, Mr Coveney said: "We need to get a deal" and that while the DUP has a role to play in supporting the British government, Ireland [and the EU] does not have a 'confidence and supply' agreement with any political party in Northern Ireland.
He said Ireland is not seeking "in any way" to threaten or undermine the constitutional integrity of the United Kingdom, but accused Sinn Féin of "spreading fear" among unionists by calling previously for a border poll.
He said there is a danger that some parties had turned the efforts to get the backstop agreement into some sort of mechanism to change the border and this was making unionists fearful.
Mr Coveney said a backstop deal must be nailed down, but there are legal hurdles to be overcome first.
Tánaiste and Minister for Foreign Affairs Simon Coveney says there must be a Brexit backstop agreement. He said the Taoiseach will never sign a withdrawal treaty that does not protect the commitments given to Ireland on the border issue pic.twitter.com/gjybslyecN— RTÉ News (@rtenews) September 22, 2018
He said he believed an agreement can be found and he trusted that British Prime Minister Theresa May is not going back on the commitments she made last December on the so-called backstop agreement.
He said the Taoiseach will never sign a withdrawal treaty that does not ensure the commitments given to Ireland on the border are not followed through on.
Yesterday, DUP leader Arlene Foster repeated her warning that her party will veto any "attempt to undermine the economic or constitutional integrity of the United Kingdom".
She said: "Our red line from day one of these negotiations has been that there can be no border between Northern Ireland and Great Britain.
"We continue our intensive work with the [UK] government to ensure that we leave the EU in a manner which protects the constitutional and economic integrity of the United Kingdom and enables us to take back control of our laws, borders and money."
Mr Coveney said there are aspects of Theresa May's 'Chequers plan' that can be worked on.
He said the UK had now committed to working on a revised text for the backstop and he called for an intensification of talks between the UK and the EU Brexit teams.
Sinn Féin President Mary Lou McDonald said: "The backstop, as agreed in December, was to secure the interests of our economy, our people and our agreements. It is a common-sense solution to the British Brexit. It would deliver for all our people, north and south.
"It is clear the DUP has a reckless disregard for the economy, agreements, livelihoods and jobs of the North.
"They do not represent the views of the majority of people nor the interests of the economy.
"The days of unionist veto are gone and will not be replaced by a Tory veto," said Ms McDonald.
Earlier, Britain's Foreign Secretary said the European Union should end its blanket refusals of British proposals in the Brexit talks.
Jeremy Hunt said any EU belief that Britain would capitulate was misplaced, and he called on EU leaders to "step back from the abyss".
He was echoing comments made by Mrs May yesterday, who said talks had hit an impasse and she demanded new proposals and respect from EU leaders.
Mr Hunt, who voted 'remain' in the 2016 referendum on EU membership, said that people in Britain were increasingly content to leave the bloc without a deal.
"If the EU's view is that just by saying no to every proposal made by the United Kingdom, we will eventually capitulate and end up either with a Norway option or indeed staying in the EU, if that is their view then they've profoundly misjudged the British people," he told BBC radio.
"We may be polite, but we have a bottom line. And so they need to engage with us now in seriousness."
Taoiseach Leo Varadkar also said he does not believe there will be a no-deal Brexit, saying he is working with other European leaders to avoid such a scenario.
Mr Varadkar said he is working to secure a deal before the end of the year, but preferably sooner.
Britain is due to formally leave the EU on 29 March 2019.