TORONTO -- Premier Kathleen Wynne was on the defensive from the start of the only leaders' election debate Tuesday, forced to apologize repeatedly for the gas plants scandal and defend soaring electricity rates.

Wynne said voters have a right to be angry over the $1.1 billion the Liberals spent to cancel two gas plants prior to the 2011 election, admitting "the public good was sacrificed for partisan interests."

She said there had been a breach of trust between her government and the people, and vowed it wouldn't happen again.

NDP Leader Andrea Horwath said the Liberals betrayed voters and wasted billions of dollars, calling corruption the central issue of the election campaign.

Horwath said the change from former premier Dalton McGuinty to Wynne doesn't matter because "corruption in the Liberal party runs deep."

Progressive Conservative Leader Tim Hudak said the Liberals cancelled the gas plants just to save seats in the last election, and raised other scandals at eHealth Ontario and the Ornge air ambulance service.

Hudak had to defend his plan to cut 100,000 public sector jobs while also promising to create one million new jobs over eight years, with both Horwath and Wynne accusing him of bad math.

With all three leaders talking over each other at times, Horwath said voters "don't have to chose between bad ethics and bad math."

The leaders will face a total of six questions from voters, starting with a question for Wynne about why the Liberals should be trusted with workers' money for a new provincial pension plan given the waste at the gas plants.

The next questions focused on Ontario's high electricity rates and on the math behind Hudak's million jobs plan.

The party leaders were greeted by cheering supporters as they each arrived at the CBC Broadcast Centre in downtown Toronto for the 90-minute debate.