ALP won't be Senate rubber stamp: Shorten

Opposition Leader Bill Shorten has defended Labor dragging out a parliamentary debate on changes to the way Australians vote for senators.

"This is not reform, this is how the Liberals design themselves to keep in power," he told ABC radio on Friday morning as the upper house neared sitting 24 hours unbroken.

If the changes were in place at the last election Tony Abbott would have been able to get his 2014 budget through parliament, Mr Shorten said.