No help from the Greens for May 3 budget

The Greens won't support the federal government recalling parliament early for a May 3 budget.

The minor party understands Senate President Stephen Parry is able to instruct the upper house to sit on that date - a week earlier than scheduled - but then it's up to senators to agree or overturn the decision with a vote.

The Greens also want Labor to support a debate of their marriage equality bill on Thursday, rather than agree to a move by Liberal Democrat David Leyonhjelm to bring on an earlier vote which they have dismissed as a "grubby tactic".

Prime Minister Malcolm Turnbull said it was critically important changes to the way Australians vote for the Senate cleared parliament this week.

"The only focus we have for the Senate's work is directed at ensuring that this, the most important institution in our democratic system, the parliament, is more democratic, more transparent, more accountable," he told reporters in Canberra.

Government leader in the lower house Christopher Pyne said no-one he spoke to in his Adelaide electorate over the long weekend had raised the issue of bringing forward the budget.