Prime Minister Malcolm Turnbull has signalled support for Bill Shorten's plan to overhaul the federal electoral system with fixed four-year government terms and plans to meet with the opposition leader in a bid to forge a bipartisan consensus.

Mr Turnbull called Mr Shorten to discuss the proposal on Sunday, shortly after the Labor leader used a television interview to call for a new cross-party push towards a referendum to change the constitution.

Government sources denied Mr Turnbull offered Mr Shorten bipartisan backing for the proposal, noting there were a lot of "complicating issues" to sort out. However, a spokeswoman for Mr Turnbull confirmed the pair spoke about "several matters", including the four-year term proposal. "The two agreed to discuss the matter further when they next meet," she said.

Mr Shorten said the three-year electoral cycle of the federal system was "out of whack" with the states - which have mostly adopted fixed four-year terms - and too often led to short-term policy making.