HALIFAX -- Thousands of Nova Scotians cast ballots in advance voting Saturday as the three party leaders spent the early part of their long weekend scouring the province for votes.

The Liberals spent Saturday promoting their promise to improve access to affordable housing as leader Stephen McNeil elaborated on his party's pledge to expand rent supplements.

"Social security is having a safe, affordable place to call home, but it's also the right thing to do," McNeil a news conference in Dartmouth. "This is taking care of some of the most vulnerable citizens in our province."

McNeil said the proposed three-year, $18-million investment will begin in 2018 and aims to shorten the waitlist for affordable housing by 30 per cent.

The Liberal plan, which was unveiled as part of the party's platform earlier this week, would top up the total amount spent on the program to nearly $30 million a year within four years. The current rent supplement is around $250 on average, and officials have said the plan could see a boost for those on the lowest incomes to the $300 to $400 range.

The premier said the province's affordable housing initiatives, which have been funded in partnership with the federal government, are the kinds of investments that could be on the chopping block under the Progressive Conservatives' platform.

Tory leader Jamie Baillie toured the southwest part of the province on Saturday while he pitched a plan to restore $1.5 million in funding to a police program to increase the number of officers patrolling the streets.

The program also supported initiatives like mental health training for officers, community policing and crime prevention, according to a PC party statement.

Baillie criticized the Liberal government for cutting the program's funding by 10 per cent, suggesting it could lead to an uptick in crime.

"Nova Scotians should feel safe and secure in their own homes and communities," Baillie said in a statement. "McNeil can talk all he wants about finding efficiencies -- a cut is a cut. This puts community safety at risk and makes it more difficult for Nova Scotian families to live healthy, productive lives."

McNeil deflected the attack at Saturday's news conference, saying the Liberals are investing in a "long-term strategy" to reduce crime by improving Nova Scotians' quality of living.

NDP leader Gary Burrill put forward a strategy to protect Nova Scotia's natural landscape while campaigning in Fall River on Saturday.

The plan included a proposal to introduce an "Environmental Bill of Rights" that would give Nova Scotians greater say over environmental policy. Burrill said under NDP leadership, the province would emerge as a "world-wide leader" in the fight against clime change.

"When it comes to our environment, Stephen McNeil has no vision," Burrill said in a statment. "We will put in place the needed protections and investments to ensure our future generations will also be able to enjoy our resources."

While the party leaders traded barbs by news release on the campaign trail, Elections Nova Scotia reported that more than 4,000 voters ticked their ballots in the first three hours of advance polls opening on Saturday.

Districts have seen a stready stream of electors on the first of seven days of advance voting, the agency said in a statement, and 20,000 Nova Scotians had already cast their votes as of mid-afternoon Saturday.

Election day is May 30.