John Swinney’s warning of a populist surge if his Government’s Budget is not agreed is “preposterous”, the leader of the Scottish Tories has said.

The First Minister will use his first major speech of 2025 to call for opposition parties to back his tax and spending plans, laid out last month.

He warned against MSPs and parties voting against the Budget to prove “some nebulous – and ultimately highly damaging – political point”, suggesting such a decision could feed “the forces of anti-politics and populism”.

First Minster John Swinney will make his first major speech of the new year on Monday (Andrew Milligan/PA)

But Scottish Conservatives leader Russell Findlay rubbished the claims, suggesting his party’s red lines are based on bringing down taxes, which are typically higher in Scotland than elsewhere in the UK for those who earn more.

“That’s just preposterous, absolutely preposterous,” he said when asked about Mr Swinney’s comments.

“We believe in cutting taxes responsibly, we believe that people who earn and work hard to earn for their families should keep as much of that money as possible.

“This is not radical stuff.

“This is actually responsible and sensible, and most people agree with that.”

Mr Findlay went on to criticise the First Minister’s engagement with his party in the Budget process.

“I wrote to John Swinney twice. He doesn’t answer my letters, he doesn’t answer my calls,” he said.

“My colleague (Tory finance spokesman) Craig Hoy has sat down with the Finance Secretary and attempted to put forward what we’re proposing, which is very serious and credible and fully costed plans to reduce the tax burden on hard-working Scots.”