TORONTO – Ontario’s governing Liberals claimed Monday to have found a costing error in the NDP election platform, marking yet another attack on the third party that has been gaining momentum, as the New Democratic leader stood by her plan and ruled out any possibility of a coalition to keep the Tories from seizing power.The province’s election campaign has increasingly seen the Liberals take aim at the NDP after months of focusing their attacks on the Progressive Conservatives led by Doug Ford.Liberal Premier Kathleen Wynne said just because her party and the NDP have similar values, doesn’t mean she won’t ask questions about their platform.“We have to have the same degree of scrutiny applied to all of our plans. That’s what this is about,” Wynne said at a campaign stop in Toronto where candidates who were the province’s finance minister and treasury board president outlined what the Liberals called the New Democrats’ “miscalculation.”The Liberals claimed the NDP platform defunds hundreds of millions in apprenticeship programs, women’s shelters and efforts for the implementation of legalized cannabis, among other things.“I think this is about the NDP making a mistake,” Wynne said. “I think the NDP believes that the things they’ve left out are important. But the fact is they’re not included in their plan. There’s no way when you look at their plan to be able to discern how they would pay for them.”The NDP countered that the figures in their platform were accurate, with leader Andrea Horwath saying the Liberals were being “pretty dishonest” with their criticism.“This is a party which has consistently challenged the independent officers of the legislature, not agreeing with the auditor general, not agreeing with the financial accountability officer,” she said.“I want to assure people that the NDP numbers are in fact correct.”Several polls have suggested the Progressive Conservatives have the most support ahead of the June 7 vote and the Liberals, who’ve been in power for 15 years, are lagging behind the New Democrats.While neither Wynne nor Horwath want to see a Ford government form next month, the possibility of a coalition between the two left-leaning leaders if the Tories win a minority was ruled out Monday.Horwath said there is no way she would join forces with the Liberals — appearing to go further than when she was asked Sunday about the possibility.“I am unequivocally saying I have no interest in partnering up with that party,” Horwath said. “They have consistently made decisions that were in their own political best interest, decisions that were in the best interest of the well-connected Liberals and high-income earners that tend to be their friends.”Ford, meanwhile, said Ontarians don’t want a “backroom deal” that would keep Liberals in power.“They don’t want the NDP making a backroom deal to prop up the Liberals,” he said at a stop in Niagara Falls. “They’re the same. When you look at the NDP who destroyed this province, then you look at the Liberals and how they destroyed this province, people want change.”Wilfrid Laurier University political science professor Barry Kay said the Liberals’ focused attack on the NDP on Monday is a bad sign for the governing party.“The NDP is moving up in the polls so the NDP is the party the Liberals are losing their votes towards,” he said.“They have to start fighting back. At the beginning of the campaign they hoped that it was basically a two-horse race … between the Liberals and Conservatives, but that is not the way the most recent polls have gone.”In their scrutiny of the NDP platform, the Liberals said the New Democrats didn’t factor in government spending announced between last year’s budget and this year’s fiscal plan, creating a hole of at least $3 billion in their platform.Horwath said the NDP plan was based on new spending programs the Liberals promised in their 2018 budget — substituted with the party’s campaign pledges. She added that her numbers have been verified by a former parliamentary budget officer.The Liberals’ own deficit projections have been called into question by the financial accountability officer and the auditor general, though the Liberals chalk that up to a difference in accounting methods.— with files from Colin Perkel and Liam Casey.