After weeks of campaign-style promises and announcements, the official 30-day Ontario election campaign kicked off on Monday.

Liberal Leader Dalton McGuinty officially delivered the writ of election shortly after noon to newly installed Lieutenant-Governor David Onley, effectively dissolving parliament.

Political party signs began popping up on lawns across the province and the party leaders took to the streets.

McGuinty visited students at Elder Mills Public School in North York on Monday morning and hammered home his commitment to public education and to his election promises.

"The fact of the matter is that we kept the overwhelming majority of our promises. That's how we've been able to deliver such essential change in education, for example, that's how we got those class sizes down,'' McGuinty said.

A day earlier, party leaders traded verbal jabs, with McGuinty listing his successes in public education, while his main opponent Progressive Conservative Leader John Tory called the Liberal leader the most prolific promise-breaker of modern times.

Tory cited the health premium and delay in closing the province's coal-fired power plants as two of the most serious examples of McGuinty breaking his word.

"It's going to be about leadership and that's between me and Mr. McGuinty," Tory told CTV on Monday.

"Who do people believe they can trust to do what they say they are going to do, to keep their word and to have the kind of competent leadership the province needs to steer it through what could be some uncertain times going forward," Tory said.

The party leaders have 31 days to convince voters that they are the ones who will lead Canada's most populous province for the next four years.

McGuinty is trying to form the second straight majority Liberal government, a feat that hasn't been accomplished in 70 years, while Tory is taking his first crack at the province's top job.

Long-time NDP Leader Howard Hampton, meanwhile, says he would be happy if voters elect a minority government, shifting the balance of power.

Hampton declined to put a price tag on how much his campaign promises will cost.

"We will outline later this week all those details and I'm sure you'll be very happy to see exactly how those details fit together," Hampton said on Monday.

However, the NDP Leader did attack McGuinty's promising-keeping record.

"That's where all the promises were broken and people need to know that,'' Hampton said on Monday.

"I'm excited because after four years of disappointment and broken promises from the McGuinty government, hard working women and men will finally have their say.''

Green Party Leader Frank de Jong is also hoping for a minority government. He says another election in a couple of years will give Green members a better chance of getting into the legislature.

Keeping with his party's environmentally conscious platform, de Jong has decided against a campaign bus and will instead travel across the province on his bicycle. He maintains all issues in the Ontario election come back to the environment.

"The Green Party is a 20-year-old success. We've been talking about climate change, toxic contamination, anti-nuclear power and preventative health care, walkable communities and transit for twenty years and finally everyone realizes that all issues in the is election are green issues," de Jong said on Monday.

The Liberals will spend the next month trying to maintain and add to their 67 seats at Queen's Park. The Conservatives hold 24 seats entering the campaign, and the NDP has 10. There is one Independent and a single vacancy.

There are 107 ridings up for grabs on Oct. 10 -- four more than the last election in 2003.

Referendum

For the first time in the Ontario's history, the date of the election has been known long before the writ was dropped because of legislation passed in 2005 establishing fixed election dates every four years.

Voters this year will also get an extra ballot, to be cast in the province's first referendum in more than 80 years.

The referendum question is: "Which electoral system should Ontario use to elect members to the provincial legislature?'' Options will be the existing so-called "first past the post'' electoral system, or a mixed member proportional system.

The proposed mixed member proportional system would give citizens two votes -- one for the political party of their choice and another for a local candidate.

Advocates say electoral reform would bring a balance of power in the legislature that better reflects the popular vote.

With a report from CTV's Paul Bliss and files from The Canadian Press