Negotiations with opposition parties are expected to begin this week after Ms Forbes had to unexpectedly present the government's draft budget last week in the wake of Derek Mackay's shock resignation.
However today Scottish Liberal Democrat leader Willie Rennie, who said he is due to meet with Kate Forbes on Tuesday, said negotiations would only be successful if she took "the roadblock of independence out the way, because that would cause massive damage."
He added: "We also have concerns about the climate emergency and mental health but we will work with the SNP if we can agree, and one of the best ways of clearing the path is to take independence out of the budget altogether. We know the SNP is in turmoil on this issue, we need less turmoil and that's why we're meeting with Kate Forbes to discuss that.
"I'm not asking them to change their view on independence but to concede there shouldn't be an independence referendum this financial year and should be taken out of the budget - therefore that would open the door - and there is spending on independence in the next year, Kate Forbes acknowledged that in Parliament, so to take that out and there's a way forward.
"Take the roadblock of independence out the way because that would cause massive damage - guarantee there's no spending on independence that's a constructive way ahead."
The cost of staging the independence referendum in 2014 amounted to just over £15.8 million. However while the budget, delivered by public finance minister Kate Forbes, outlined preparations for a second independence referendum as one of the Scottish Government’s “priorities” for 2020-21, it did not spell out how much would be spent on plans to "develop and disseminate detailed information on the case for independence".
Today, the party's co-convener Patrick Harvie, said the SNP needed to re-prioritise its spending on road infrastructure as well as protect local government spending to win his party's backing.
"We've set out publicly that the Scottish Government needs to protect local government, to address the climate emergency, and free bus travel for young people has been Green policy for a while. However the Scottish Government hasn't built political consensus with anybody prior to this budget and they really should have done given the tight timescale this year so Kate Forbes has one brief opportunity now to try and achieve political consensus."
He added: "Protecting local government is key and I think every political party in opposition and many SNP activists and councillors are deeply concerned councils are going to be in breach of their legal duties for some of their services."
He said he also wanted more investment in climate emergency measures like renewable heating and energy efficiency, but also investment in public transport. "We've got a multi-billion pound road building programme at the moment which will make traffic congestion worse not better. If we're building more capacity in the road network we will generate more traffic.
"Even the government's own infrastructure commission has advised against increasing capacity in the road network - so that's billions of pounds that can be looked at again in the existing budget which could be invested in public transport instead."
Scottish Conservative MSP Liam Kerr said Mr Harvie's proposals would have a "serious negative impact on road safety and economics" and "was not the way to go".
He added: " We have a set of fully costed proposals that are reasonable - and we would go further given the choice in government - but we'll be the adults in the room to get a deal. What we can't do, is make Scotland even more unattractive than the SNP have already made it."
And Scottish Labour's Rhoda Grant said that as the budget stood her party could not back it. "We were looking for free bus travel for young people, not just for their benefit but for the environment and to change patterns of behaviour into adulthood, and we were looking for a fair settlement for local government but it's facing another huge cut.
"There's no deal unless they change their plans, but this is a draft budget so there's time for them to do the right thing."
The Scottish Government has been contacted for comment.