Shirley-Anne Somerville was appearing at a Budget scrutiny meeting of Holyrood’s education committee on Wednesday morning and repeatedly defended the Scottish Government’s funding decisions.
Mr Rennie claimed the Budget indicated a £268 million cut to the core council budget, equating to a cut of around £100m to education based on the suggestion education is “half” of what local authorities fund.
He also labelled the SNP MSP’s responses “rubbish”.
A Holyrood briefing document states that, with inflation, the core revenue budget for councils will reduce by £284m, or -2.6 per cent, in real terms between 2021/22 and 2022/23, heaping pressure on councils to find additional funding streams.
In a fierce row, Mr Rennie accused the education secretary of “complacently accepting” a £100m cut to her budget, which he said would undermine her work.
He said: “I might have to because it is quite clear the Cabinet secretary is not going to make any efforts for more funding for core school budgets, and it is your job to stand up for education and you’re not making that case.
"Why on earth are you sitting here complacently accepting the fact that the Cabinet secretary for finance is effectively cutting £100m from your core budget?
"It is undermining the work that you are doing. Why are you not making the case for this?"
Responding, the SNP minister defended her Government’s Budget and said it was “fair”.
She said: "I think the Government overall has a fair settlement for education and for local government.
"He can demand more action is taken, but he has to suggest where that money will come from if he is not satisfied with the Budget proposals that are being brought forward by the Government.”
All of Scotland’s 32 council leaders of all political allegiances criticised the Government’s Budget when it was announced in December, stating it represented a serious cut to their overall funding.
However, ministers have claimed it is one of the largest settlements for local government and that core budgets had been protected in cash terms.
Earlier in the evidence session in Holyrood, Mr Rennie pressed Ms Somerville on why she was not “spitting mad” at the potential cut to the education budget, and criticised her use of statistics, which compared per pupil funding in Scotland with England.
He said: “You have made various promises that you are funding in terms of extra teachers and other things, and, of course, you should because they were your election promises and you should fund those, but that doesn’t entitle you to cut £100m from their core budget.
"This is not about England, this is about Scotland. I don’t want the comparison with elsewhere because I care about the pupils in Scotland, so why on earth is she not angry about this?
"I mean I’m angry, I can’t believe you are cutting budgets at this time, so why are you not angry about it. That’s what I don’t understand about this, it’s very managerial.
Ms Somerville responded: "I don’t accept the premise of the figures that you are using.”