UK Prime Minister Boris Johnson is all set to meet leaders in North Ireland on Wednesday, the key battleground in Britains’s fight to leave the European Union and the focus of increasingly tense rhetoric on both sides of the Irish Sea.

Johnson arrived in Belfast on Tuesday night amid warnings from Irish leaders that his vows to leave the EU with or without a deal, risks breaking up the United Kingdom.

He will hold talks with Northern Ireland’s main political parties to discuss the restoration of the British province’s power-sharing government which collapsed in January 2017.

Johnson told Ireland’s prime minister, Leo Varadkar on Tuesday that the “backstop” plan was unacceptable, putting him at odds with both Dublin and Brussels, which insists the deal is not open for renegotiation.

“If they really can’t do it then clearly we have to get ready for a no-deal exit,” Johnson said.

In response to Johson, Varadkar said that Johnson’s plan to renegotiate the deal by a deadline of October 31 was “totally not in the real world”.

Johnson visited Scotland on Monday, responding to independence calls from Scottish First Minister Nicola Sturgeon by saying that the United Kingdom represented a “global brand”.

Last week, Sturgeon said that Scotland where a majority of voters opted to remain in the EU in the 2016 referendum, needed an “alternative option” to Johnson’s Brexit strategy.

He also visited Wales on Tuesday as part of the whistlestop tour of the United Kingdom designed to signal his commitment to keeping the union whole after Brexit.

In his first speech as Prime Minister on July 24, Johnson pledged to bring Britain out of the EU by October 31, saying “no ifs, no buts”. He also warned that there would be a hard Brexit if the EU refused to renegotiate the withdrawal agreement.

Johnson will also announce a 300-million-pound investment to drive economic growth in Scotland, Wales and Northern Ireland.