Scots are “scunnered” with the divisions over Brexit and independence, with a growing tranche of “politically homeless” voters now seeking an alternative to the extremist approach of the two main UK parties, according to Rennie.

The Tories can no longer be trusted to protect the Union, as Brexit trumps everything else, while Labour has simply “given up” in Scotland, Rennie has told Scotland on Sunday.

He claims the Lib Dems are having their best campaign in a decade and the twin-pronged appeal to stop Brexit and Scottish independence is striking a chord with the majority of voters.

Willie Rennie canvassing for the Lib Dems yesterday in the Newkirkgate shopping centre in Leith . Picture: Lisa Ferguson

Rennie believes many “moderate Conservatives”are exasperated over the hardline Brexiteer regime at the helm of the party, with Boris Johnson’s proposed deal with EU leaders creating a customs border down the Irish Sea.

“The kind of Boris Johnson cleaving of the moderate wing of the Conservatives has left those people politically homeless and many of them have come to us as well,” said Rennie.

“It’s not just activists. There are real voters out there as well who have said they don’t want politics that goes off the extreme, we want something new and Jo Swinson’s offered that.”

The Prime Minister’s current EU withdrawal deal carries the same threat to the Union which last prompted Johnson and his then Scottish secretary, David Mundell, to raise concerns over Theresa May’s deal, said Rennie.

“They are – in their own words of last year – ‘prepared to undermine the United Kingdom.’” Rennie said.

“You can’t really trust the Conservatives to stand up for the United Kingdom any more because they’re fixated by Brexit that they will do anything in order to deliver it.

“For moderate, reasonable, traditional Conservative voters, if they already haven’t left the Conservative Party, they should think seriously about it and they’ll find a home with the Liberal Democrats.”

The Lib Dems teetered on the brink of electoral oblivion in the years following the Coalition, but the party’s hardline anti-Brexit stance has seen it recover to finish second in this year’s European elections, prompting new leader Jo Swinson to claim she is a realistic contender to be prime minister.

The party has targeted a tranche of key seats across Scotland, including SNP leader Ian Blackford’s Ross, Skye and Lochaber constituency and the North East Fife seat of nationalist Stephen Gethins which has a majority of just two.

Rennie is equally withering in his assessment of Labour after Scottish leader Richard Leonard saw his opposition to an independence referendum undermined by the UK leadership. Jeremy Corbyn has made it clear that he could allow a repeat of the 2014 vote on leaving the UK in the latter years of a Labour government.

“That is devastating for Scottish Labour,” said Rennie. “That’s moved an awful lot of people, who have just given up on the Labour Party – and they look as if they’ve given up.

“Jeremy Corbyn has almost conceded that Labour in Scotland can’t be relied on to increase to what they used to be, so he’s just going to do a deal with the SNP in order that they get into power.”

Meanwhile, the Lib Dems’ formal policy to cancel Brexit in the unlikely event that Swinson gets her hands on the levers of power has raised eyebrows. Some argue it would be undemocratic to overturn the result of the 2016 referendum without going back to the people directly on the issue.

But Rennie points to a “scunneration factor” among the wider voting public over Brexit and insists that Johnson’s claim of an “oven- ready” deal will just kick off years of fresh talks on trade and future relations.

“People are scunnered with it,” he said. “The Prime Minister’s solution is just to get it done, whatever it is, no matter how damaging it is to the United Kingdom, no matter how much it costs.

“We’re saying let’s not do the damage, let’s make it stop, let’s protect the United Kingdom, let’s protect our finances and the economy and just make it stop – let’s revoke Article 50. So we’re appealing to those people who have had enough. We just think our solution is more economically responsible.”

Double-digit Tory leads in the polls almost a fortnight into the campaign point to a majority for Johnson on 12 December which would make Brexit a certainty. But the Scottish Lib Dem leader says the Remain camp is still strong, with the Lib Dems also ready to back a People’s Vote as part of a broader coalition.

“We’ve had one million people on the streets of London and six million people who have signed that revoke petition,” he said.

“The energy in the Remain camp is really big just now. It’s strong and powerful.”

Scots seem to be shifting towards independence as an alternative to Brexit, with the country now split down the middle on the issue, according to most polls. But Rennie accepts that while many are “flirting with independence” at the moment, but insists it won’t last.

“When the spotlight shifts on to the practicalities of independence, when people realise that actually we’re supposed to learn the lessons of Brexit, that breaking up is hard to do – breaking long-term economic partnerships when your economies and your peoples are intertwined is a damaging and difficult thing to do…

“When people see that, and see that will come with independence as well in spades, then they will pull back.

“The answer to breaking up one political union is not to try to break up another.”

And although the SNP is riding high in the polls at the moment, Rennie insists that a litany of failures in domestic policy could see it come unstuck. Recent NHS scandals over infection outbreaks at Glasgow’s Queen Elizabeth Hospital and the delayed Sick Kids hospital in Edinburgh, along with concerns over educational standards and train performance are among the areas where Nicola Sturgeon will be vulnerable at the next Holyrood election in 18 months.

“Westminster’s a basket case just now, so everything else gets hidden in the shadows of that,” Rennie added. “But as soon as the spotlight starts turning on the performance of this [Scottish] Government there will be a dramatic change in public opinion.

“This Government has got a terrible record and as soon as people see it in the run-up to 2021 the spotlight will be big on their performance.”

Election 2019: Willie Rennie makes pitch to ‘homeless’ Conservatives