The Miles government hoped to have a signed and sealed plan to deliver a major upgrade to the ageing Queensland Sports and Athletics Centre (QSAC) for the Games.

However, it may not come to fruition after the opposition leader poured cold water on the proposal.

David Crisafulli had consistently claimed the Liberal National Party would establish an independent infrastructure authority to decide on venue plans if it won the October election.

Polling indicates Mr Crisafulli is on track to end Labor’s nine-year reign.

Mr Crisafulli on Thursday said the decision on QSAC should be up to the independent body but indicated which side of the fence he was on.

“I would be very surprised if an independent body, that wasn’t acting on a political knee-jerk decision because of pressure on upgrading a venue, would say ‘(dumping) over $1.5 billion on temporary stands in the scrub would be a good option’,” he said at the Tourism, Aviation and Transport Summit in Brisbane.

“Only one person is saying that is the only option, I don’t share that view.”

Mr Crisafulli’s comments follow his previous refusal to confirm a position on whether or not to upgrade QSAC.

“Let’s have a look at what’s not just the best legacy play,” he told reporters in March.

The QSAC upgrade had been a hot topic after it was ruled out by an independent infrastructure review which recommended a new $3.4 billion stadium in Victoria Park become the 2032 centrepiece.

Premier Steven Miles ignored the advice and opted to give ageing facilities QSAC, the Gabba and Suncorp Stadium a facelift.

Mr Miles on Thursday doubled down on his decision to upgrade QSAC, with a business case already underway to establish final costs.

He reiterated that if he remained in power then the decision was final and the business case was to answer how the upgrade would be done, not if.

“Brisbane 2032 is letting us deliver legacy infrastructure all across Queensland,” Mr Miles said at the summit.

The government had come under fire on multiple fronts after Brisbane’s Lord Mayor lambasted the delay in finalising the plan, saying it had been 1135 days since the city won the bid.

“That’s quite a shocking figure to think that we had the longest period of time that any city has been given a head start and some of that has slipped through our fingers,” Lord Mayor Adrian Schrinner told a Committee for Brisbane lunch on Wednesday.

“We need to do better. What we’ve got at the moment and the discussion around the Olympics and legacy is undercooked and we’re not making the most of the opportunity ahead of us.”

But even the government’s fiercest critic, Mr Crisafulli, believed there was plenty of time to deliver a world-class Games.

“Sydney didn’t win the bid until ’93 and Sydney created in ’95 an independent infrastructure coordination authority … I think that model works,” he said.

“I believe we do have time.”