Truss says early poll could help

An early election of the lower house and full Senate remains a possibility, outgoing Nationals leader Warren Truss says.

Prime Minister Malcolm Turnbull has been weighing up whether to call a double dissolution election based on the failure to get laws to clean up union corruption through parliament.

One scenario could involve a July election, which would need to be called in early May.

Mr Truss, who announced on Thursday he would retire at the next election, said a double dissolution election made sense.

"It's obvious the government is having great difficulty getting its legislative program through the parliament," Mr Truss told reporters in Canberra.

He said there was a chance the government would get a "more workable" Senate and it would bring senators' terms better in line with those of lower house MPs.