HALIFAX -- Nova Scotia's Liberals released an election platform Wednesday that included a total of $1.08 billion in spending commitments and tax cuts over four years, along with promises to do more for those on income assistance.

The platform is based on last month's budget that was tabled but not voted on in the legislature and contains a number of promises that were already announced on the campaign trail.

"Our plan is comprehensive, it's credible and it's costed," Premier Stephen McNeil told a gathering of party faithful at a Halifax hotel.

"It promotes innovative new programs that support families, seniors and communities."

The Liberals had already promised several major initiatives in the budget that are also part of their platform, including a pledge to reduce taxes for 500,000 low- and middle-income earners and a pre-primary initiative for four-year-olds that would include 9,000 children by 2020 at an annual cost of about $49 million.

There is also previously announced money to twin 100-series highways, upgrade gravel roads, and create collaborative care centres.

Among the millions in new spending is funding for low-income rental supplements and income assistance.

Party officials said a promised rent supplement expansion beginning in 2018 is aimed at reducing the wait list for affordable housing by an additional 30 per cent. It would top up the total amount spent on the program to nearly $30 million a year by the fourth year of the Liberal plan.

The current rent supplement is on average around $250, and officials said the plan could see a boost for those on the lowest incomes to the $300 to $400 range.

Under the plan, the standardized household income assistance rate would be increased by an overall total of $20 million a year by the fourth year, with individual increases of two per cent on the rate for those who can work and five per cent for those who can't work because of a disability. That would allow people to keep more of what they earn -- as much as an additional $300 a month.

"This is part of the evolution that is taking place ... to transform income assistance to make sure there is not a disincentive to join the workforce," said McNeil.

The platform also contains two significant shifts in health care that include allowing doctors to choose where and how they practise and a signalling that a Liberal government is open to creating more long term care beds if needed, although no numbers or costs were included.

McNeil said the moves don't mean the Liberals are moving away from either an emphasis on collaborative care models for areas that lack doctor coverage, or home care for seniors in order to keep people home longer.

The Liberals are also pledging to cover the cost of oral cancer medications for those not fully covered by insurance until a program can be worked out with the other Atlantic provinces to do so.

NDP Leader Gary Burrill said the Liberal plan didn't go far enough in addressing the needs of those who need the most help.

"There is zero here on addressing the crisis of hunger in Nova Scotia ... on addressing the crisis of indebtedness of students and tuition and a zero on the crisis that is undermining so many of our hospitals ... the absence of there being any new long-term care beds," said Burrill.

Speaking for the Progressive Conservatives, Halifax-Citadel-Sable Island candidate Rob Batherson said the Liberal plan lacked credibility because of McNeil's broken 2013 campaign promises. Among them: His infamous doctor for every Nova Scotian pledge, and a promise to extend the province's film tax credit that was subsequently axed.

"Why would anybody believe what's in his platform this time?" said Batherson. "It's as if after three-and-a-half years of failure and broken promises he wants a do-over."

The Liberals were the last of the three main parties to officially release a platform for the May 30 vote.