Horwath is making several campaign stops around the Greater Toronto Area today, saying the party is hearing from some traditional Liberal or Progressive Conservative voters who say this time they will vote NDP.
She says Premier Kathleen Wynne "has been running from the Liberal record of scandal and she cannot get away from it."
Police investigating the alleged destruction of government documents related to the cancellation of two gas plants by the Liberals have asked for key records from the legislature.
Ontario Provincial Police are seeking visitors' logs and other records in the investigation that earlier determined some hard drives in the former premier Dalton McGuinty's office had been wiped clean of data.
Sgt. Pierre Chamberlain said the order delivered to the legislature gives 10 business days to produce the documents.
The NDP and the Progressive Conservatives are calling on Wynne to make those records public immediately.
Horwath says voters are "tired of the stench of corruption in this province and they want it cleaned up."
"This election is about corruption," she said in Toronto. "This is a referendum on corruption, this campaign."