Prime Minister Malcolm Turnbull has thrown his leadership rival to Labor’s wolves, putting up little to no defence to a serious charge of a breach of the constitution that could, if proven, strip Peter Dutton of his seat.

After days of damaging attacks on the Prime Minister for instability and turmoil, the opposition switched to doing Mr Turnbull’s dirty work for him.

The attack was simple. Mr Dutton gets cash from a family trust that owns two Brisbane child care centres – reportedly $5.6 million between 2010 and 2018. This might breach Section 44 of the constitution, which prohibits politicians from receiving any “pecuniary interest” from the government.

Christopher Pyne jumped up to block the first question, but he was waved away by Mr Turnbull.

“Do you want to answer it?” a surprised Mr Pyne whispered to the PM.

“I’m happy to,” he replied.

Mr Turnbull said he would seek advice. Later in question time he revealed Mr Dutton had not sought the advice of the Solicitor-General, the government’s chief legal adviser.

Will the PM refer Mr Dutton to the High Court?

It was a short reply: “The Member for Dickson [Peter Dutton] has advised me he has legal advice he is not in breach of Section 44 and I have no reason, therefore, to believe that he is.”

When pushed on whether he personally had seen the legal advice, Mr Turnbull made no attempt to deflect. He said no, in three different ways.

“I have not seen the advice … but [Mr Dutton] has confirmed to me he has legal advice but I have not seen it. I have not been provided with a copy of it.”

After question time, Attorney-General Christian Porter reportedly asked the Solicitor-General to look at the issue.

But Labor’s question time attack did not stop there. It invited Treasurer Scott Morrison to criticise Mr Dutton’s idea of exempting power bills from the 10 per cent GST. Mr Morrison complied, willingly offering up the estimated cost to the budget of $7.5 billion over four years.

“That $7.5 billion would either not then go to the states, or the commonwealth would have to pay that additional money to the states,” the Treasurer said.

Labor’s other tactic was to target each senior minister who had offered their resignation after backing Mr Dutton in Tuesday’s failed leadership bid, to goad them on whether they retained confidence in the PM.

With few exceptions, the answers were short, and focused more on the government’s record than Mr Turnbull’s personal successes.

“Yes, I do,” Health Minister Greg Hunt replied. “I also believe deeply and strongly in the record of this government.”

“The answer, of course, is yes,” Human Services Minister Michael Keenan said.

Then Angus Taylor, Minister for Law Enforcement and Cybersecurity. “The answer is yes, I do.”

A big jeer greeted Citizenship Minister Alan Tudge, whose answer was more coded: “I have given the Prime Minister my assurance that he has my support.”

The biggest laughter was reserved for Mr Morrison, who was accused – based on media reports – of the “trifecta” of “doing the numbers” from Mr Turnbull, Mr Dutton and himself.

But his answer was more convincing than some of the others, judging by the quiet in the room.

“Absolutely … the Prime Minister has always enjoyed my support.”

Importantly, he did not deny the charge of gathering numbers for a challenge.

Steve Ciobo’s reply was the shortest: “Yes.”

As expected, Wednesday’s question time was again overshadowed by Liberal Party leadership tensions. Mr Dutton confirmed earlier in the day that he was building the numbers for a second tilt at the leadership.

Given Thursday is the last sitting day for a fortnight, it could come as early as then.

There was also a barb from Labor at Mr Turnbull’s admission, long awaited, that he would stop trying to legislate the big-business tax cuts.

“Given that the Prime Minister is pretending to dump his signature policy to hang on to his job, when are they going to dump you?” Labor’s Bill Shorten thundered.

Mr Turnbull repeated the line that the “iron laws of arithmetic”, namely the obstinance of crossbench senators, had doomed the bills.

What was new was that he appeared to admit they were also electorally unpopular. “We do not foresee any change in public sentiment on this matter,” he said.

This apparent change of tack was mirrored by some of his ministers, who countered on traditional Labor policy areas of the NBN and spending on health and welfare.

A federal election looms, possibly as early as October this year, according to analysts, with proof from recent by-elections that several of the Coalition’s policies – now jettisoned – were electoral poison.