The Liberal Democrats have said they will only back the Scottish Government’s budget plans if it rules out a second independence referendum.
Scottish Lib Dem leader Willie Rennie is due to start budget negotiations with the SNP Government next week.
But he said his party would only take part if Nicola Sturgeon ditched plans for another referendum.
Speaking at the Liberal Democrat’s autumn conference in Dunfermline on Saturday, Mr Rennie said the Brexit “chaos” and the SNP’s own Growth Commission report had “obliterated the case for independence.
“We are simply not going to vote for an SNP budget that keeps an independence referendum on the table,” said.
The minority government will need the support of at least one opposition party if it is to pass its tax and spending plans for next year.
It has previously had the support of the Scottish Greens but Mr Rennie claimed: “The Greens are threatening to stand up to them this year.”
He added: “Liberal Democrats have worked together with others where we can.
“We hunt for partnership when it’s in the interests of the country.
“But independence is against the interests of the country.
“For Liberal Democrats to be in, independence has to be out.”
First Minister Nicola Sturgeon shelved plans for a second referendum after the SNP lost 21 seats in last year’s general election, with its share of the vote dropping from 50% to 37%.
She has previously said she will make a decision on whether or not to call for another vote on independence in the autumn.
Responding to Mr Rennie’s comments, a spokesman for Finance Secretary Derek Mackay said: “When it comes to the budget Willie Rennie should be more concerned by the fact that this year two MSPs from his group of five voted against him to support the Scottish government’s budget.
“We will bring forward a budget that invests in our economy and delivers for public services right across the country – if the Lib Dems vote against that because of their constitutional position it will say a lot about where their priorities lie.”
Mr Rennie also used the conference to announce his party is backing a campaign for children in Scotland to start school at the age of either six or seven rather than four or five.
He said international evidence showed under-sevens needed a play-based approach to learning.
“Almost nine out of ten countries in the world start formal education at the age of six or seven,” he said.
“Only a fraction join Britain at such an early age.”