There has been mixed reaction from Ireland's politicians as Boris Johnson was announced as Britain’s new Conservative Party leader.
There has been widespread concern among some Irish politicians over how Mr Johnson's leadership will affect Ireland and the situation regarding the Irish border and Brexit.
Mr Johnson, who will become Britain’s Prime Minister later today, has recently compared solving the border issue with the moon landing, and in a BBC interview in 2018 compared it with the border between Camden and Westminster in London.
Government politicians were quick to welcome the new prime minister in waiting, making it clear they were happy to work with Mr Johnson, but Brexit remained the key priority in each message.
Taoiseach Leo Varadkar posted on social media: "Congratulations to Boris Johnson on his election as party leader. Look forward to an early engagement on Brexit, Northern Ireland and bilateral relations."
Later, Tánaiste and Minister for Foreign Affairs, Simon Coveney, first retweeted Michel Barnier, the EU's chief negotiator, who had written about reworking "the agreed Declaration on a new partnership in line with #EUCO guidelines", before writing his own post.
"Congratulations to Boris Johnson on becoming leader of the UK Conservative Party - we will work constructively with him and his Govt to maintain and strengthen British/Irish relations through the challenges of Brexit," Mr Coveney said.
However, opposition politicians took a different stance.
Sinn Féin Brexit spokesman David Cullinane says it came as no surprise that Boris Johnson will become prime minister, but called on the Irish Government to hold steadfast in Brexit negotiations.
"We'd be very concerned that Boris is not going to make any serious effort to reach any kind of accommodation with the European Union," he said.
"He seems to believe the Irish government and the European Commission is going to blink on these matters, I don't think there's any appetite for any changes to the Withdrawal Agreement, but it remains to be seen what will happen.
"The chances of a no-deal Brexit have been increasing, because it was quite obvious that while there is no appetite in the House of Commons for no deal, there's no sense what they're in favour of," Mr Cullinane added.
"Boris has been talking up a hard crash, in some respects encouraging a hard crash, that would be a disaster for Britain, a disaster for Ireland, I don't see any good in that for anybody, but again - that's outside our control, what we can do is that we hold the Irish government to account and they hold firm."
People Before Profit TD Richard Boyd Barrett has said that the elevation of Boris Johnson to leader of the Tory Party and thus prime minister of the United Kingdom presents a "clear and present danger to Ireland" and "brings the prospect of no-deal and the imposition of a north-south border much closer".
He called Mr Johnson a "genuine danger" because of his "callous disregard for the impact of no-deal on Ireland, his allegiance to Donald Trump, his disgraceful comments about UK soldiers' actions on Bloody Sunday and his extreme right-wing views on just about every issue".
He added that Mr Coveney needed to tell Boris Johnson "in the clearest possible terms that a hard border between the north and south of this country is simply not an option".
Likewise, Irish Labour Party leader Brendan Howlin said: "With 100 days until Brexit, it is time now for all politicians in Ireland to hold our nerve and be steadfast in defending our vital interests."