LONDON/HELSINKI (Reuters) - Prime Minister Boris Johnson’s Brexit plan was facing mounting legal, political and diplomatic challenges on Friday as Ireland accused Britain of being unreasonable and former British leader John Major sought to stop the suspension of parliament.

FILE PHOTO: Britain's Prime Minister Boris Johnson meets with Prime Minister of Japan Shinzo Abe on day three of the G7 Summit in Biarritz, France, August 26, 2019. Andrew Parsons/Pool via REUTERS

The ultimate outcome of Britain’s tortuous three-year Brexit crisis remains unclear with options ranging from a frantic departure without an exit deal or a last-minute agreement to an election or referendum that could cancel the whole endeavor.

Johnson, the face of the Vote Leave campaign in the 2016 referendum, has promised to lead the United Kingdom out of the European Union in two months with or without a divorce deal, a threat he hopes will convince the bloc to give him the exit deal he wants.

In the eye of the Brexit maelstrom, though, Johnson was under mounting pressure: opponents in parliament were plotting to tear up his Brexit plans or topple his government, while his suspension of parliament was under scrutiny in the courts.

Johnson’s bid to get the insurance policy for the Irish border changed were bluntly dismissed by Dublin which said London was being totally unreasonable.

“Boris Johnson is outlining a very clear and firm position but it is a totally unreasonable position that the EU cannot facilitate and he must know that,” Irish Foreign Minister Simon Coveney said in an interview with Ireland’s Newstalk radio.

German Foreign Minister Heiko Maas said Britain should make concrete proposals as soon as possible but that the EU could not imagine reopening the Withdrawal Agreement that Johnson’s predecessor Theresa May agreed with Brussels in November.

Britain insisted it had made proposals on the border backstop and that it was “untrue” to suggest it had not.

The government said British negotiators would hold twice-weekly talks with EU officials next month in an attempt to rework the Brexit agreement that Britain’s parliament has repeatedly rejected.

BREXIT ENSNARED

With just two months until the United Kingdom is due to leave the EU, Johnson’s decision to ask Queen Elizabeth to suspend parliament was under challenge from three separate court proceedings.

The queen on Aug. 28 approved Johnson’s order to suspend parliament from as early as Sept. 9 to Oct. 14, a move that ensures parliament would sit for around four days less than it had been expected to.

Former Prime Minister John Major, whose 1990-1997 premiership included the 1992 disorderly exit of the pound from the Exchange Rate Mechanism, asked to join one of the proceedings to block Johnson’s order

A Scottish court will hear arguments on Sept. 3, a case brought by campaigner Gina Miller will be heard on Sept. 5 and a Northern Irish court will hear a separate case on Sept. 6.

Ultimately, the cases could be combined to go to the Supreme Court - the final court of appeal in the United Kingdom which hears cases of the gravest constitutional importance.

“Legal proceedings can be fast-tracked as the judges in the case determine,” Robert Blackburn, professor of constitutional law at King’s College London, told Reuters.

“If the case of those bringing the legal proceedings wins, the Supreme Court could quash and/or declare unlawful the Privy Council order authorizing the forthcoming prorogation,” said Blackburn.

In parliament, the battle for Brexit was due to begin in earnest on Sept. 3 when lawmakers return from their summer break and will try to either topple the government or force through a law designed to prevent Britain leaving the EU without an exit deal.