The Ontario NDP has been stuck in third place for six straight provincial elections.

The party hasn't won more than 21 seats since 1990, and has been unable to win more than one-quarter of the popular vote since the electorate tossed out Bob Rae's one-term NDP government a generation ago.

Even with Premier Kathleen Wynne's low approval ratings suggesting that Ontario voters could be in a mood for change after 14 years of the Liberals, the New Democrats have continued to struggle in recent polls.

Despite all that, NDP leader Andrea Horwath is professing optimism about her party's chances when Ontario votes in 2018.

"We're quite excited about this election and our ability to actually bring the real kind of change that people expect from an NDP government," Horwath said Tuesday in an interview with CBC News.

"I think people are looking for something other than the Liberals, that's for sure," she said. "There's a lot of disappointment in Kathleen Wynne and the way she's handled her time in office over the last couple of years. I've heard it in downtown Toronto and I hear a visceral negative reaction across the province."

Ontario NDP leader Andrea Horwath. (CBC)

If 2018 does turn out to be an election that's all about change, Horwath's task will be to persuade voters that the NDP best represents that change. Her interview gives a taste of how she'll try to do that, in part through taking on the Progressive Conservatives.

"By looking to the Tories, you won't see much change," said Horwath. "In fact, you'll see things get even worse."

She said voters will need to ask themselves "whether the PCs are the answer," pointing out that PC leader Patrick Brown spent nine years as a backbench MP with Stephen Harper's federal Conservatives.

"Conservatives cut and they privatize. They believe in small government. They believe that public services should be farmed out to the private sector. We've had enough of that under Kathleen Wynne and the Liberals," Horwath said.

Wynne's Liberals are certainly trying to win back the hearts of "progressive" voters with a series of significant policy announcements in recent months: pharmacare for those under 25, expanded rent control and a $15 minimum wage.

The NDP will be trying to remind voters of other aspects of the Liberal record: privatizing Hydro One, overcrowded hospitals and spending taxpayer money on self-congratulatory advertising.

Horwath unveiled the NDP's plan for Pharmacare in April: coverage of the 125 most commonly prescribed medicines, for patients of all ages. (Twitter)

"We're not on the side of workers just before an election, we're on the side of workers all the time," said Horwath. "We believe that when people look around for the change that they want, they're going to see an NDP that is always on the side of everyday folks."

The challenges facing the NDP in the 2018 campaign are numerous. It has consistently trailed the other two main parties in fundraising. The party has also struggled to garner widespread support from the labour movement, which has in the post-Mike Harris years tended to rally behind the Liberals as a means of keeping the PCs out of power.

A sign that the party has not yet escaped from the legacy of the early 1990s, NDP candidates tell me they still bump into voters who bring up Bob Rae at the doorstep.

When I mentioned this to Horwath, she acknowledged it still happens, but countered that a lot of time has passed since that NDP government. "There's a lot of folks who don't even know who Bob Rae is," she said.

Horwath speaks before Toronto's annual Labour Day parade in September 2016. (Martin Trainor/CBC)

Parties win elections by effectively targeting their limited resources to the ridings where they have the best chances. Typically, those are the seats where they came second in the previous election. That's the case for the New Democrats in just 21 ridings. Winning all those seats, plus hanging on to the 20 seats they currently hold, wouldn't be enough to form government. They would also need to take at least a dozen ridings where they came third in 2014 even to eke out a minority.

But the Ontario New Democrats don't have to look too far back in Canadian history to find parties that leapt fom third to first in a single election: in 2015, Justin Trudeau's Liberals did it federally, as did Rachel Notley's NDP in Alberta.

The 2018 campaign will be directed by Michael Balagus, Horwath's chief of staff and the architect of a string of NDP election victories in Manitoba.

"We have a good opportunity in this election to really show the people of Ontario that not only can the NDP win, but once we win, we can turn this province into a place we can all feel proud of," said Horwath.