Marriage vote delay 'failure of leader'

Opposition Leader Bill Shorten has told caucus members the prime minister has completely failed as a leader.

Opposition Leader Bill Shorten has blamed a failure of leadership by Malcolm Turnbull for the dragged-out same-sex marriage debate.

Mr Shorten told the first Labor caucus meeting since the winter break on Monday coalition members were doing all they could to delay a decision on marriage equality.

"There is only one reason why this failure to deal with marriage equality has dragged on as long as it has - it is because of the complete failure of leadership and weakness of the prime minister of Australia to deal with this issue," Mr Shorten told the meeting in Canberra.