Voting changes 'will alter Senate make-up'

The Liberal-Nationals coalition will be the only major player able to hold a Senate majority in its own right, preference expert Glenn Druery has told a parliamentary inquiry.

The man who helped the likes of Ricky Muir become a senator also believes planned changes to way Australians vote for the Senate spells the end of the upper house crossbench except for South Australian independent Nick Xenophon.

Micro-party senators would cease to exist and no new micro-paries would be born.

Mr Druery addressed the joint committee on electoral matters during a half-day hearing in Canberra on Tuesday.

Government legislation, which cleared parliament's lower house last week, will allow voters to cast preferences above the line on Senate ballot papers.

Mr Druery accused the Greens, who support the changes, of benefiting from a form of electoral subsidy and of bringing up the "drawbridge" on others.

"The legislation is about a tactical shifting of power. It's almost a form of electoral school-yard bullying or we don't want people like Ricky Muir playing in our sand-pit," he said.

"In the future the coalition will be the only party able to hold the Senate in its own right (and) these changes may force the Labor Party into a formal coalition with the Greens."

Liberal Party federal director Tony Nutt denied the proposal would benefit the coalition while his Nationals counterpart Scott Mitchell said the changes won't make any difference to his party.

The Australian Electoral Commission said it would need a minimum three months to implement the changes, provided they pass parliament unamended.

Constitutional law expert George Williams said the system now enabled parties, not voters, to determine the flow of preferences.

"That's not a good system because it may be parties direct preferences to flow in a way that is indeed the opposite to what a person would see as their true voting intent," he told the inquiry.

Professor Williams agrees the changes are a major improvement on the existing system, but also wants to see optional preferential voting below the line as well as above.

Prominent ABC election analyst Antony Green said the existing system had created a "herding process".

"You have been herding people above the line for the last three decades by making the choice of how to vote asymmetrical," he said.

Veteran election analyst Malcolm Mackerras warned of an inevitable High Court challenge, saying he was looking forward to it with "fear and delight".

Senator Ricky Muir lamented the half-day hearing, which has to report back on Wednesday.

"This is the most biased and unbalanced committee I've ever been in," he said.