"It's going to be forward-thinking and long-term in vision," Finance Minister Charles Sousa said Tuesday.
He appealed to the Progressive Conservatives and New Democrats to support his spending plan, but struck a less than conciliatory tone.
"I'm proud of what we will be delivering on May 1," Sousa said. "And if the opposition decide they want to go against the very initiatives the people of Ontario have asked for, that's their call.
Sousa announced the date at the same time the province's top civil servant, cabinet secretary Peter Wallace, was set to testify about the alleged wiping of hard drives in the premier's office.
The legislative committee is examining the deletion of government emails related to the cancellation of two unpopular gas plants, which the opposition say was done to save Liberal seats in the 2011 election.
Police allege 24 computers may have been scrubbed with the help of former premier Dalton McGuinty's chief of staff, David Livingston, who is under investigation for breach of trust.
The allegations have not been tested in court and Livingston's lawyer has said his client didn't break any laws.
Sousa said the timing of his announcement was coincidental, but both opposition parties called it a blatant attempt to change the channel from the scandal.
The minister was supposed to make the announcement Wednesday morning in the legislature, according to leaked documents the Tories obtained that outline the Liberals' budget rollout plan.
"This is obviously designed to distract from a potentially explosive day at the gas plant hearing," said Tory finance critic Vic Fedeli.
The Conservatives say the scandal is one more reason why Ontario needs an election, but the New Democrats — who have been just as critical of the Liberals — won't say whether they'll keep propping up the government.
NDP house leader Gilles Bisson said they want to see the budget first.
"It's not responsible for us as a party — and I don't think it's responsible for anybody else — to say we're going to do X, Y or Z without seeing what's in it and without really taking a look at what the options are," he said.
The confidence vote on the budget motion could happen as soon as May 8 or as late as June 2, according to the Liberals.
They've been dropping hints in recent days about what the budget will contain.
Premier Kathleen Wynne pledged Monday to make $29 billion available over the next decade for new transit and transportation infrastructure in Ontario.
They plan to allocate $1.3 billion a year in gas taxes and take on more debt to help pay for it, but Wynne won't say how they'll raise the rest of the money until the budget is tabled.
She's ruled out increases to gas taxes, HST or income taxes on middle-income earners, which the government defined in its recent economic outlook as workers making between $25,000 and $75,000 a year.
But the premier was tight lipped on whether those earning more than $75,000 would take a hit to fund transit.
Wynne said the budget will also outline how the province will find the money to fill the $1.3-billion hole in the province's main coffers that pay for public services.
It will be difficult to find the money for transit without new levies, given that the Liberals are already facing an $11.3-billion deficit, lower-than-forecast revenues and weak economic growth over the next 20 years.
She has said that Ontario's shares in General Motors — purchased during the recession — could be sold to build transit, roads and bridges.
Sousa also mused last week about squeezing more money out of the Liquor Control Board of Ontario, as well as Crown corporations like Ontario Power Generation and Hydro One.
The Liberals promised in last year's budget to raise money through high-occupancy toll lanes, which would allow motorists to pay to use the HOV lanes that are usually reserved for those who have one or more passengers.
The budget is also expected to re-affirm their intention to create an Ontario pension plan to bolster retirement income if Ottawa keeps refusing to enhance the Canada Pension Plan.
Also on HuffPost