Horwath shot back at Premier Kathleen Wynne while standing in front of a memorial statue of Layton, who led the federal party to a massive surge in support and official Opposition status in the last national election.
Wynne used Layton's name over the weekend to slam Horwath for refusing to rule out propping up a Tory-led minority government. Horwath, whose party has been a consistent third in the polls during this provincial campaign, said the Liberals want voters to forget that Layton would have stood against their scandal-ridden government.
"Ms. Wynne likes to talk a lot about great NDP leaders, but I can tell you the same people like Jack Layton that she talks about fought Liberal corruption all his life," Horwath said Monday.
"Jack fought the same battle that I'm fighting today and that's why I'm standing in front of this memorial to remember, to remind people exactly what Liberals are like."
Wynne launched a direct appeal on Sunday to New Democrat voters, telling them that a vote for Horwath is a vote for Progressive Conservative Leader Tim Hudak because only the Liberals have a chance at beating him on Thursday, when Ontario voters go to the polls.
"That is how far the NDP has fallen — it's not the party that it was," Wynne said. "It's not the party of Jack Layton. It's not the party of Ed Broadbent. It's not the party of Stephen Lewis."
A group of 34 current and former New Democrats, some well-known within the party, wrote an open letter earlier in the campaign, wondering if Horwath had "given up" on progressive voters by not supporting a left-wing-friendly Liberal budget and saying they are considering not voting NDP.
Broadbent was quick to fire back at Wynne.
"Partisan debate is one thing, but by invoking my name in weekend speeches and articles to attack Andrea Horwath and the Ontario NDP, Kathleen Wynne has gone beyond the pale," he said Monday in a brief statement.
"Let no one doubt: I fully support Andrea Horwath and the Ontario NDP."
Horwath honed her response as the day went on, at various campaign stops in southern Ontario.
"It's really, really clear that Kathleen Wynne doesn't know Ed Broadbent and she doesn't know Jack," she said in Wallaceburg.
It's not uncommon for federal parties to help their provincial cousins in election campaigns — federal Liberal Leader Justin Trudeau has campaigned with Wynne and Foreign Affairs Minister John Baird has appeared on the campaign trail for Hudak.
Federal NDP Leader Thomas Mulcair has only appeared with Horwath at a private campaign event, which the NDP says is a result of scheduling conflicts.
Horwath said Wynne is using Layton's name to distract voters.
"They want you to forget about their corruption. They want to forget about the billions of dollars of your money that they wasted," Horwath said. "Kathleen Wynne likes to talk a lot about great NDP leaders, but she cannot even stand in their shadows."
Though Horwath said she could not support Hudak's plan to cut 100,000 public sector jobs, nor would she support "corrupt" Liberals, she didn't explicitly rule out a coalition or propping up either party if it wins a minority government.
"I'm running to be the premier of this province," she said in Toronto when asked if she would be part of a coalition government. "I'm going to respect the people's decision on Thursday, but I can tell you for sure I will not support 100,000 families being kicked to the curb and I will not support corrupt Liberals."
At a campaign stop in Chatham she was asked again if she was ruling out a coalition.
"What I am doing is saying I am going to give the people of this province the respect of making their choice on June 12, and I really firmly believe that they should have the room to do that," she said. "On June 12 I trust that the people will make the right decision and we will have a government in this province that makes sense for the people."
Horwath did prop up the Liberals for years, and on Monday defended that support.
"I respected the decision that people made in their last election campaign that we had here in Ontario," she said in Toronto. "People voted for a minority parliament and I worked very, very hard to make that parliament deliver results for them and I'm proud of that work."
She ultimately decided to pull the plug, triggering the election, due to scandals such as the cancellation of two gas plants, which is estimated to have cost taxpayers up to $1.1 billion.