The Nationals backbencher has introduced a private member's bill to parliament that would split each state into six regions - like mega electorates - with each region voting for two senators.

"This is something that is so important," he told the lower house on Monday.

"We need for our Senate to have a constituency and to have the capacity to represent a geographic area."

Mr Joyce said in most instances, 11 out of 12 senators come from capital cities.

He also pointed out that New York has two senators while Adelaide has 11.

"We need to make sure that as the seats get bigger and bigger and bigger in the House of Representatives in regional areas, that this is offset by the capacity to get more Senate representation."

Under the plan, which was seconded by independent MP Bob Katter, no region could be bigger than 30 per cent of the state's landmass and the capital city would be confined to a single region.

Mr Joyce argues this would also help to improve indigenous representation in parliament.

The backbencher, who recently launched a failed bid to reclaim the Nationals leadership, said the proposal wouldn't warrant a change to the constitution.

It's up to parliament to change how senators are elected, Mr Joyce said.

Constitutional law expert George Williams said this was correct but he wasn't sold on the idea.

"It may be unwise, particularly because of how it will distort the voting power of some people relative to others, but I cannot see it is unconstitutional," he told AAP.

"It is possible for parliament to provide for more than one electorate per state."

Senate president Scott Ryan was quick to shoot down Mr Joyce's idea after he floated it last year.

"The current Senate is actually very reflective of the national vote despite the differences in state populations," he said.

"But this proposal would destroy that."

Australian Associated Press