TORONTO – After months of painting the Ontario election as a two-horse race, the governing Liberals acknowledged another rival Thursday, taking aim at the NDP as the third party was endorsed by a teachers’ union.The Liberals raised questions about an NDP candidate they suggested advocates cutting teacher salaries, while their leader, Kathleen Wynne, attacked the party for its perceived disdain for business.Wynne, who had previously highlighted common ground between the Liberal and NDP plans while stressing a “stark” contrast with the Progressive Conservatives, also said the New Democrats have not explained how they would implement their platform, suggesting only her party could carry out its promises.“The plan that we’re bringing forward, which is an investment in care in this province, is doable. What our plan does is it recognizes, unlike the NDP, that the whole economy is important,” she said at a Toronto hospital, her first campaign stop of the day.“I understand that there’s an ideology on the part of the NDP that says that the private sector is inherently not a good thing. I don’t adhere to that.”Numerous polls have shown lagging support for Wynne and the Liberals contrasted with building momentum for NDP Leader Andrea Horwath and her party.One observer said the sudden shift in strategy is a logical response to the polls, but may suggest the Liberals now see themselves coming in third on June 7.“It’s natural for the Liberals to shift at least part of their attention to the party that’s lapping them,” said Andrea Perrella, director of the Laurier Institute for the Study of Public Opinion and Policy.The Liberals may initially have been reluctant to burn bridges with the NDP in case they won a minority and needed support, but may now fear they won’t form the official Opposition, he said.At the same time, while the NDP appears to be gaining public support, it’s hard to see the party making inroads in cottage country or the Toronto suburbs, Perrella said. The party’s best strategy is likely to recruit new voters, he said.Wynne denied feeling threatened by the New Democrats’ apparent gains in popularity, or by the Elementary Teachers Federation of Ontario’s endorsement of the party, saying the union’s backing does not mean teachers themselves will vote that way.“We haven’t always had, as a party, the full support of all of the unions or the federations … and individual teachers make their decisions on a riding by riding basis,” she said.The Liberals nonetheless attacked a New Democrat candidate on Thursday, suggesting Marco Coletta favours a 15 per cent reduction to teacher salaries in the province.Horwath said she isn’t aware of Coletta’s comments and said teachers would be “properly paid” for the work they do under an NDP government.She also brushed off Wynne’s suggestion that her party can’t act on its promises.“One of the things that we’re prepared to do that I think Liberals have shown they’re not prepared to do is ask their richest friends and richest corporations to help us pay for the promises that we’re making. To help us pay for things like a better health care system, prescription drugs for everyone, dental care for everyone,” Horwath said.The president of the Elementary Teachers Federation of Ontario said the NDP earned the union’s endorsement because of its commitment to publicly funded education.Horwath has promised to end standardized testing of students if elected, something the teachers’ union supports.Teachers have had a strained relationship with the governing Liberals for years following a bitter contract dispute with former premier Dalton McGuinty in 2012.— with files from Shawn Jeffords.