Marathon debate in the Senate

THE SENATE MARATHON

* The Senate has been sitting unbroken since 9.30am (AEDT) on Thursday.

* Senators are debating government legislation that changes the way Australians elect senators.

* The Greens are supporting the government, which means the legislation is certain to clear parliament. When, though, is not so certain as Labor senators drag out debate with a filibuster.

WHAT THE CHANGES DO

* Voters, instead of political parties, will be able to determine their own preferences above the line on the Senate ballot paper. They will be encouraged to number six boxes, but a single vote will be valid.

* If they choose to vote below the line, they won't have to number every box - in some states that could be more than 100. Instead they only have to number 12 boxes, but any vote with six numbers will be valid .

* Abolish group voting tickets that allow micro-party candidates to win a seat in the Senate with a minuscule primary vote.