TORONTO - Premier Dalton McGuinty wants Ontario voters to believe he won't raise taxes again if the Liberals are re-elected Oct. 6, but he wouldn't say the words Monday as he launched his campaign platform.

McGuinty answered "No" when specifically asked if he would raise taxes again, but when pressed by reporters to state in a full sentence that he would not raise taxes, the premier refused to say all the words.

"Will you say it?" he was asked repeatedly.

"I just did," said McGuinty. "We will not."

The Liberal leader also declined to say why voters should believe him personally after he promised before the last two Ontario elections not to raise taxes, and did so both times, first with a health-care tax of up to $900 per worker in 2004 and with the harmonized sales tax in 2009.

"Ontario families have made their contribution," he said. "They have done their share, and what an enormous difference that has made."

The opposition parties said McGuinty cannot be trusted when it comes to tax hikes, which the Progressive Conservatives called the elephant in the room.

"Dalton McGuinty is a liar," said PC candidate Andrea Mandel-Campbell standing in front of a giant inflated red elephant.

"He said he would not raise taxes, not once but twice, and he will raise taxes again."

The New Democrats also said voters won't trust McGuinty.

"He can make promises till he's blue in the face, but he's got an eight- year track record," said NDP candidate Paul Ferreira.

"One of the reasons people have decided it's time for a change is because the premier has broken his word a number of times. The trust factor is gone."

McGuinty defended his government's spending of tax dollars to improve health care and education, themes which figured prominently again in the Liberal platform.

The most expensive, high-profile promise in the McGuinty platform is a 30 per cent reduction in college and university tuition fees for families earning less than $160,000 a year.

"This is about more than just winning the election, it's about winning the future," said McGuinty.

"There's simply no better investment a society or economy can make than in its youngest generation by equipping them with the best possible skills and giving them a great education."

The grants of $1,600 for each university student and $730 for each college student will begin Jan. 1. The money will go to the colleges and universities, which will be required to lower the tuition bill for each student.

The grants will apply to about 86 per cent of the 90,000 full-time students in Ontario's post-secondary institutions, making them widely available to the middle class for the first time, said McGuinty.

The Liberals, who waited until two days before the start of the campaign to launch their platform, said the tuition grants will cost taxpayers $200 million this year, growing to $486 million a year by 2015-16.

However, the Canadian Federation of Students said the grants were not the tuition fee cut they had been looking for.

"We're just a little confused about a system that would allow for tuition fee increases while also saying that tuition fees are too expensive," said Sandy Hudson, chair of the federation's Ontario branch.

"Why put money in to cover money that you're making students pay more of? It just seems like a very confusing scheme to us."

It was the Liberals that drove up Ontario's tuition fees to the highest in Canada, said the NDP.

"This is the same government that let Ontario become 10th out of 10 in per capita post-secondary funding," said Ferreira. "Can we trust them now? I don't think so."

The Liberal platform, a large portion of which was obtained by The Canadian Press on Sunday, also promises to create another 60,000 university spaces at three new campuses, but it doesn't say where those campuses will be built.

The Liberals say they will expand GO trains to all-day service from early morning to midnight, but it will take 10 years before all the new tracks are laid and everything else is in place for the increase to kick in.

The Liberals also plan to spend $12 million to provide a tax credit to employers who hire immigrants for their first job in Canada. The credit applies to new Canadians who live in Ontario and have been in the country for up to five years.

The Tories said that will hurt the thousands of Ontario residents who don't have a job and are looking for work.

"We need to think about how we're going to create jobs for them, and instead we're providing a $10,000 subsidy for people from outside of Ontario," said Mandel-Campbell. "This is unfair."

The Liberal platform also promises another $60 million for more support workers to buy three million more hours of home care for seniors.

Greenpeace Canada criticized the Liberal platform for not mentioning plans to spend at least $33 billion on two new nuclear reactors and to refurbish old ones, instead emphasizing their push for solar and wind power projects.

"The Liberals deserve praise for their green energy policies, but omitting mention that the majority of their spending will go to building new expensive reactors misleads voters," said Greenpeace's Shawn Patrick-Stensil.

"Clearly the Liberals know that their nuclear plans aren't a vote-getter while green energy is."