Smiles in the Senate as MPs return early

Given they sat for 28 hours straight last time parliament met, senators were in a surprisingly chirpy mood after being forced to return to Canberra three weeks early.

An eager Family First senator Bob Day was the first crossbencher to arrive in the upper house ready for work on Monday.

Former Palmer United Party team mates Jacqui Lambie and Glenn Lazarus embraced while Ricky Muir was visited by Labor's Sam Dastyari who wedged himself on the cross bench.

They were getting ready for the arrival of the governor-general and the rest of the 150 MPs required by Sir Peter Cosgrove for a joint sitting of both chambers of parliament.

In a little-used constitutional procedure, parliament was prorogued mid-session to consider what Sir Peter said was legislation critical to the government's reform agenda.

The government wants the Australian Building and Construction Commission restored and a Registered Organisations Commission established to oversee tougher governance rules on trade unions.

Rejection by the Senate would trigger a double-dissolution election on July 2, Prime Minister Malcolm Turnbull has vowed.

"My government regards these measures as essential for the rule of law in our workplaces," said Sir Peter, as Labor MPs and senators - keen for a fight - jeered.

"My government also regards these measures as crucial to its economic plan for promoting jobs and growth," he went on as coalition MPs shouted "hear, hear".

And with that, Sir Peter's job was done.

He shook Mr Turnbull's hand and that of deputy PM Barnaby Joyce before walking over to do the same with Opposition Leader Bill Shorten.

Left hanging was Labor deputy Tanya Plibersek.

"Know your place," someone on the opposition benches joked.

As MPs dispersed from the Senate chamber, Treasurer Scott Morrison had a hug and a kiss for Liberal colleague Bronwyn Bishop who stood out in a bright orange jacket.

The 73-year-old former Speaker was dumped by her party at the weekend in a preselection race for the northern Sydney seat of Mackellar.

If push comes to shove in the Senate, Bishop's remaining time in parliament will be numbered in days, not weeks.