A group of 34 high-profile Ontario NDP supporters say they're "deeply distressed" by the direction party leader Andrea Horwath has taken in the election campaign and are seriously considering not voting for the party.

In a letter to Horwath obtained by Evan Solomon for CBC's Power & Politics, the group of longtime supporters, including Michele Landsberg (columnist and wife of former Ontario NDP leader Stephen Lewis) and former federal candidate Winnie Ng, warn she may lose their support "and the support of thousands of others." The email was dated May 23.

"From what we can see you are running to the right of the Liberals in an attempt to win Conservative votes," the letter reads.

"It is not clear whether you have given up on progressive voters or you are taking them for granted."

The letter goes on to say the NDP has risked the election of "the most right-wing and vicious leader of the PCs since Mike Harris," referring to Tim Hudak, and that the proposed Liberal budget was the most progressive in recent Ontario history.

They seem to be running on a kind of right-wing populism, not at all on party policy, or in any way talking about social justice or democracy. - Judy Rebick

The warning comes a day after the NDP platform was released and during a campaign where Horwath's decision to force the election has been criticized by NDP insiders such as Gerry Caplan, along with Liberals.

Long-time activist Judy Rebick is one of the NDP supporters who signed the letter.

"We just don't get it," she said. "Where's the NDP? Where is the party that we all supported?

"They seem to be running on a kind of right-wing populism, not at all on party policy, or in any way talking about social justice or democracy."

The NDP issued a statement in response to the letter later Friday night.

“Progressives cannot turn a blind eye to corruption because it weakens the very foundations of our democracy. We need to renew democracy by guaranteeing transparency and accountability. Sunlight is the best disinfectant," said NDP campaign co-chair Gilles Bisson.

"The support our leader is getting from people has never been warmer, our ranks never been stronger. We’re proud to stand for raising the minimum wage, increasing childcare spaces, lowering tuition, and supporting caregivers.”

In a phone interview, Bisson said some of the people who signed the letter are not real NDPers and that it is a Liberal attempt to take attention from their party's scandals.

Mobile users can click here to read the full letter to Horwath.