Premier Dalton McGuinty is dodging a committee investigating Ontario's troubled air ambulance service to keep a lid on the scandal ahead of two potentially game-changing byelections next week, the Conservatives charged Wednesday.

The all-party legislative committee only wanted an hour of McGuinty's time, but he blew them off for a photo op at an empty school, said Tory Frank Klees, who sits on the committee.

The Sept. 6 byelections are the premier's shot at a majority government, and the last thing he wants is for voters in Kitchener-Waterloo and Vaughan to be reminded of the Ornge scandal, Klees said.

"We're promising the premier that we're going to continue to raise this issue ... to remind the voters in both ridings that this is a premier who presided over the festering of one of the most expensive scandals that this province has ever had," he said.

"And he is refusing to even answer questions. Why?"

McGuinty defended his decision not to appear before the committee, saying it's up to Health Minister Deb Matthews to answer questions about Ornge. She's appeared three times, he added.

"I think they've had some 54 witnesses who have attended to date and there have been countless hours of testimony," McGuinty said after touring a Toronto school.

"I think what we really need from the committee at this point in time is a set of recommendations that we might be able to act on."

McGuinty said he's already answered questions about Ornge, including when he first met ousted CEO Chris Mazza, and is prepared to answer more during question period.

The Tories took him up on his challenge, using almost all their allotted time in the legislature to fire questions at the premier about Ornge.

"If the premier's got nothing to hide, then he should be OK with showing up to the committee — it's as simple as that," said NDP Leader Andrea Horwath.

The Conservatives insist the committee is the only forum where McGuinty would have to testify under oath about what he knew about Ornge before it became front-page news.

Ornge is currently under a criminal probe over financial irregularities and has been the subject of a scathing report by the auditor general, who criticized the Liberals for failing to oversee the service despite giving it more than $730 million over five years.

The committee has heard explosive testimony about an alleged kickback scheme, exorbitant salaries, badly designed medical interiors in new helicopters and what one politician called "heavy-duty nepotism" at Ornge.

The province's chief coroner and a panel of experts are also taking another look at deaths involving Ornge over the past six years to determine whether transport may have played a role.

Premier can’t be forced to testify, Klees says

McGuinty and Mazza are the only two witnesses who have refused to appear before the committee, Klees said. But Mazza was under medical care for mental health issues, and finally testified after the committee issued Speaker's warrants to compel him to appear.

McGuinty has no excuse and knows that as premier, he can't be compelled to testify, Klees said.

But the premier said there's a big difference between himself and Mazza in terms of being available to answer questions.

"He doesn't appear in this legislature on a regular basis for question period," he said in the legislature. "I do."

Questions have also been raised about whether unregistered lobbying on behalf of Ornge was done by well-connected Liberals.

McGuinty maintains that he met Mazza once in October 2005, when he visited residents of the remote First Nations reserve of Kashechewan who were evacuated during the tainted water crisis. Mazza was his guide on a tour through the emergency medical assistance team tents.

McGuinty said he couldn't recall meeting Mazza again, but acknowledged the possibility that he may have run into him and doesn't remember because he meets thousands of people at political events.

Mazza testified that he was introduced to McGuinty at a fundraiser, where he talked to him for 15 minutes about his ideas for Ornge.

He said the introduction was made through Alfred Apps — a man with strong ties to both the Ontario and federal Liberal parties — who was working as a lawyer for Ornge at the time.

The committee heard from Mazza's former executive aid, Jay Lebo, who says he provided business advice to the ex-CEO and was regional operations manager at Ornge.

He echoed the testimony of many former employees in describing Mazza's behaviour as "autocratic" and "volatile."

"It was his way or the highway," Lebo said. "Dissent in the organization was not tolerated. You either did as you were told with a smile or you were shown the door."

He said he was also asked to give auditors false information about expenses. He wrote the business justifications but didn't backdate them as instructed, Lebo said.

He said he was also ordered to lie to paramedics by denying them vacation and telling them it was for operational requirements, when in fact it was to "mitigate the hemorrhaging budget" for overtime.