OPPOSITION Leader Bill Shorten has said Labor would not support an early recall of the Senate, further complicating the situation if the government wants to call a double-dissolution election.

The government is considering bringing the budget forward a week to May 3 to give itself extra time to get supply through, which would be necessary for a double dissolution.

But whether the Senate could be recalled would ultimately be up to that house, where the government is in a minority. With Labor and the Greens, and also no doubt most of the other crossbenchers, opposed, the numbers are not currently there.

The Senate has a couple of options to prevent an early return. It could vote against the standard motion at the end of the sitting week that includes giving the Senate president discretion to vary the due date of the next sitting. Or, if the president did seek an early return, a majority of senators could oppose that, making it unlikely he would press the matter.

While opposing an early return, Shorten reaffirmed that Labor would not block supply, so one option would be for the House of Representatives to pass supply in the week the budget was delivered and then push it through the Senate on May 10 – when the Senate is due to sit, and the day before the deadline for calling a double dissolution.

However, that timetable would not seem to leave time to put to the Senate the legislation for the Australian Building and Construction Commission (ABCC), which the government would want as a double-dissolution trigger bill. If it does not put the bill to the Senate, this would weaken its argument that the bill had “failed to pass” and so could be a trigger.

The government and the Greens have done a deal to give priority this week to legislation to introduce optional preferential voting for the Senate. On Tuesday they voted down moves from crossbenchers to bring on the ABCC legislation and to debate same-sex marriage. The Greens called on Labor to make available its private members’ time on Thursday to debate same-sex marriage.

Treasurer Scott Morrison, asked in Question Time whether the budget would be delivered on the scheduled date, said it was on May 10.

Earlier Morrison confirmed that the government will tighten tax concessions for superannuation. Details will be announced before or in the budget. The government intends to legislate to define the purpose of superannuation being to provide income in retirement to substitute or supplement the age pension, rather than as an instrument of creating wealth to hand on.

Morrison said any changes the government made to superannuation would be about that purpose.

“How tax incentives are structured will no doubt form part of these changes but the changes will be about delivering a fairer and more sustainable retirement income system for our 21st-century economy building on the pension reforms in last year’s budget.

“It’s not about revenue raising. It’s not about higher taxes to fund higher spending. It’s about a better retirement incomes system.”

Tuesday’s Essential poll showed the Coalition and opposition on 50-50 on two-party terms.

Michelle Grattan, Professorial Fellow, University of Canberra

This article was originally published on The Conversation. Read the original article.