The European Union deal that David Cameron has negotiated is "about appealing to careerist Tory MPs", but the benefits the UK receives by staying in the EU is a "no brainer", Liberal Democrat leader Tim Farron will say.
Farron will seek to step up his attack on those who wish to remove Britain from the EU when he addresses the Scottish Liberal Democrat conference in Edinburgh on Saturday.
Farron will say that his is the only party "wholly in favour" of keeping Scotland in both the UK and Europe.
With the referendum on the UK's EU membership set for June 23, the Lib Dem leader will also say prominent Tories in favour of leaving are "only one lurid blazer away" from being part of Eurosceptic former Tory leadership candidate John Redwood's fantasy cabinet.
The Conservative Cabinet is split over whether the UK should stay part of the EU, with Justice Secretary Michael Gove, Northern Ireland Secretary Theresa Villiers, Work and Pensions Secretary Iain Duncan Smith, Culture Secretary John Whittingdale and Chris Grayling, the leader of the House of Commons, among those who have declared support for the Leave campaign.
While Farron will tell the conference the Lib Dems "very much want reform" of the EU, he will claim the deal Cameron has negotiated "is about appealing to careerist Tory MPs, who were selected by Europhobic party members, to persuade them to vote to remain".
But he will say that "it is not going too well", adding: "Gove, Villiers, Grayling, IDS, Whittingdale and (Employment Minister) Priti Patel.
"They're only one lurid blazer away from John Redwood's fantasy cabinet," the Press Association reports.
Farron will continue: "The thing is, so far as the Leave side is concerned, they are the sensible wing. Because I turned on my telly the other day to see Nigel Farage and George Galloway sharing a platform, sharing a joke and sharing prejudices... telling us that we should turn our backs on Europe."
He will argue that the "decision to remain or to leave is the biggest in generations for our country", adding: "While the renegotiation was successful. It wasn't central. It's not central in the minds of most people.
"People across Scotland, across all of Britain, will make up their mind on much bigger issues.
"Given that Europe is the world's biggest market, will we be more prosperous if we remain or leave?
"Given that this is a dangerous and uncertain world, are we safer and more secure by staying alongside our closest friends and neighbours? Or turning our backs on them?
"Given the scale of international challenges of a global economy, climate change and the refugee crisis - are we better to face these together or alone?"
Farron will insist the answer to each of these questions "is a no brainer", saying: "If you want a Britain that is prosperous, secure, a Britain that matters, then you are voting to keep Britain in Europe.
"The only party that is wholly in favour of a Scotland that is prosperous and secure within Europe and the United Kingdom is the Liberal Democrats."