The Coalition has reaffirmed it could call a double-dissolution election if it wins government but is blocked from repealing the carbon tax.

Opposition MPs on Saturday repeated their view that September's election would be a referendum on the carbon tax, and that a joint sitting would be a fallback option if they're prevented from scrapping the policy.

Opposition frontbencher Christopher Pyne confirmed that leaked details of the Coalition's environment policy, including the timeline for rolling back the carbon tax, were correct.

The reports included calling a double-dissolution election within five months if the Coalition's efforts to abolish carbon pricing were thwarted.

When asked about the reports, opposition climate action spokesman Greg Hunt said if the Coalition won the federal election, voters would expect Labor to respect their mandate.