At an appearance in Hamilton and later at a rally in Waterloo, the leader of the third party emphasized the New Democrats as a realistic alternative to what she called the "corrupt" Liberals under Kathleen Wynne and the Progressive Conservatives under Tim Hudak.
"I need to be really clear here, people do have a choice, I am running to be the premier of this province," Horwath said outside an advance polling station in Hamilton where she and her son cast their ballots.
"Kathleen Wynne's Liberals have spent more time using your money to protect their interests than they have on delivering for you. Mr. Hudak is not the kind of leadership that this province needs."
Both Wynne and Hudak have been dismissive of the NDP in trying to frame the election as a two-way race between their parties.
Hudak has staked out his ground with proposals to lower corporate taxes and slash the public sector. Wynne has styled her Liberals as the only party that will protect the province from what she frames as the Tories' drastic cuts.
But Horwath shrugged off suggestions that voters might ignore the New Democrats to try to stop the Liberals or PCs from winning office.
Instead, she said New Democrats would not waste taxpayer dollars as the Liberals have done with decisions such as cancelling two gas plants to save party seats at a cost of up to $1.1 billion.
Nor would the NDP slash 100,000 public sector jobs, she said, a direct jab at Hudak's plan to cut 10 per cent of the public sector.
"This election really is about what kind of Ontario we want," Horwath said. "We will respect your tax dollar and we will invest them in your priorities."
Part of the NDP plan to avoid the money mismanagement scandals that have plagued the Liberals — which Horwath says prompted her to trigger the election by not supporting the budget — involve establishing a financial-accountability office and a minister responsible for finding $600 million in annual savings.
Horwath is under pressure to increase the NDP's seat count from the 21 they held at dissolution.
The politician struck a feisty tone as she made her promises on Saturday, saying she made no apologies for being "upset" over the state of Ontario's government.
"The Liberals have behaved in a way that wastes precious tax dollars. That makes people upset, it makes people angry," she said.
"What I can tell you for sure is we do not have to go back there."
Voting day is June 12.