The Irish border issue is the key to derailing Brexit, Scottish Liberal Democrat leader Willie Rennie has said.
Mr Rennie said difficulties in finding a solution which protects the Northern peace process could sway public opinion towards abandoning plans to leave the European Union.
The Lib Dem leader put forward the argument as he addressed the David Hume Institute in Edinburgh as part of a series of speeches by Scotland's party leaders.
He insisted people were rethinking their decision to leave the EU, stating that the Irish border, the economic impact of Brexit and the "inability of the UK Government to set out a clear position", were key factors.
An ICM survey conducted for the Guardian newspaper and published last month found 47% of people would favour having a final say on Brexit once the terms of the UK's departure are known.
"In 2018 people are thinking again," Mr Rennie said.
"Now in 2018 we can feel the early consequences of Brexit and have also seen the evidence of what is likely to happen next.
"We have seen how the architects of Brexit in the Conservative Party have no clue what they want or how they are going to get it."
He added: "It is therefore little surprise that people are beginning to think that they have had enough of it."
Mr Rennie continued: "I actually think Ireland is the key to this."
The UK Government wants to avoid a hard border on the island of Ireland and a customs border between the North and the rest of the UK.
"It's almost impossible to have a close relationship between Ireland and Britain, which is necessary for the Irish peace process, and have the divergence that some of the hard Brexiteers want," Mr Rennie said.
"That's where the nub comes - the Irish border is going to be the real test.
"I think that's part of the answer, and it potentially could force Britain to be be much, much closer to Europe, and we might actually end up with a situation where (people say) why do we bother breaking up if we're going to be that close."
The Lib Dem leader also used his address to reissue a plea to Labour and the SNP to get behind a campaign for a referendum on the final Brexit deal.
Scottish First Minister Nicola Sturgeon has said a second referendum is becoming "hard to resist" but she has stopped short of joining the campaign for one.
Labour leader Jeremy Corbyn has previously indicated he does not support a final deal ballot, while shadow chancellor John McDonnell said on Sunday it would be better to have a general election.
"The time is coming fast when people should have the freedom to refuse a bad Brexit deal," Mr Rennie said.
"People need to get on board. The national interest can be saved."