TORONTO -- NDP Leader Andrea Horwath responded to calls from the Liberals to adjust their platform on Monday, saying that the party will stick with their platform even though it'll cost $1.4 billion more per year than originally expected.

Liberal Leader Kathleen Wynne said Horwath has a responsibility to correct the error -- in which the NDP counted a $700-million reserve fund as revenue rather than as an expense -- as soon as possible.

But Horwath said the party was still committed to it's platform and said that they would deliver on all of its promises.

"We've fixed the problem that was identified," said Horwath, speaking to reporters after a campaign event in Brampton, Ont., that was attended by hundreds of supporters from southern Ontario.

"I'm confident that everything in our platform is achievable, should people give us the honour of governing in Ontario, we will make life better for everyone."

The numbers have since been fixed in the online version of the New Democrats' platform, but Wynne said the issue goes deeper.

"People are counting on us as politicians in the province," she said. "They're counting on us to be able to put forward a plan, and to be able to be clear about what the impact of that plan would be."

The NDP initially said they would run a $3.3-billion deficit in 2018-2019, but with the error corrected that number jumps to $4.7 billion.

That's compared to the Liberals, whose budget projects a $6.7-billion deficit and the Progressive Conservatives who have indicated that they will likely run a deficit in their first year in power, but have not released a fully costed platform.

Horwath was joined by federal NDP Leader Jagmeet Singh on Monday's rally, with more than 50 NDP candidates from southern Ontario also joining the event.

Campaigning from a Mexican restaurant in Toronto on Monday, Wynne said she doesn't see how the NDP will be able to continue running on the same platform.

"That changes everything about what the NDP plan says, and what is possible," Wynne said. "So (Horwath) will have to answer questions about how she will go forward, and the impact of that mistake on the overall plan."