Finance Minister Andy Kerr has denied that plans to change the way in which local councillors are elected amount to "a political fix".
The move would replace first-part-the-post voting
The introduction of a proportional representation (PR) voting system is a key part of the coalition deal between Labour and the Liberal Democrats.
Mr Kerr and his deputy, Lib Dem MSP Tavish Scott, were questioned by the local government committee on Tuesday.
The minister rejected criticism from Labour backbenchers.
Under the executive's Local Governance Bill, councillors would be elected under the Single Transferable Vote (STV) method of proportional representation.
That would see three or four councillors being elected from new multi-member wards.
But an expert group appointed by the executive has called for between two and five councillors to be elected from each ward.
Despite the agreement with their coalition partners, many Labour backbenchers and councillors are bitterly opposed to the changes to the current first-past-the-post system.
Andy Kerr said the "political fix" accusation was beyond the pale
However, Lib Dem backbenchers have warned that the coalition could be at risk if the executive fails to press ahead with its bill.
Labour MSP Michael McMahon accused the Scottish Executive of agreeing the deal to ensure a working majority in parliament.
Addressing the finance minister, he said: "Do you accept that it's a political fix and do you believe that a political fix is a good general principle on which to take forward a bill?"
Mr Kerr said: "I don't call that a fix, I call it an arrangement we have in the Scottish Parliament where discussions are held and partnership agreements are sought.
"I think the term 'fix' is beyond the pale in regard to how we came to that conclusion."
The minister rejected claims by Labour MSP Paul Martin that voters would find it difficult to understand the new electoral system.
Mr Kerr also said the executive was not in favour of holding the Scottish Parliament and local government elections on separate days to highlight the different electoral systems.