Clive Palmer and the micro-parties that will hold the balance of power in the Senate from July are threatening to play havoc with Prime Minister Tony Abbott's legislative agenda if the government gives in to growing calls to reform the voting system.

New South Wales senator-elect David Leyonhjelm told Fairfax Media he would not co-operate with the government if his political party was ''put out of business'' by scrapping the current ''above-the-line'' voting system.

Clive Palmer says calls to reform the voting system are "an attack on democracy". Credit:Glenn Hunt

The system has been blamed for the rise of ''preference harvesters'' such as the Motoring Enthusiast Party, which got its candidate Ricky Muir elected on a little more than half of 1 per cent of the primary vote in Victoria.