TORONTO -- NDP Leader Andrea Horwath's attempts to make the party more business friendly -- and electable -- are alienating the party base, which is why some core New Democrats are complaining loudly about her campaign for the June 12 Ontario election, political analysts said.

"They're upset that the NDP is talking about the middle class not about the working class," said University of Toronto political science professor Nelson Wiseman.

"You can see it in some NDP circles where people are not terribly enthused."

In the strongest signal yet that Horwath is losing the support of some of the party faithful, she received an open letter Friday from 34 current and former New Democrats -- some well-known within the party -- who said they were "angry" that she did not support the Liberal budget on May 1, triggering an election.

Calling it "the most progressive budget in recent Ontario history," they wrote: "From what we can see you are running to the right of the Liberals in an attempt to win Conservative votes. It is not clear whether you have given up on progressive voters or you are taking them for granted."

The group went on to say that they were "seriously considering not voting NDP" this time.

Horwath's campaign countered by pointing out the New Democrats have gone from 10 seats in the legislature to 21 under her leadership.

Professor Henry Jacek of McMaster University in Hamilton said Horwath angered some NDP supporters by offering tax cuts to small businesses to offset a promised hike in the minimum wage to $12 an hour. They also didn't approve of her decision to purchased a front-page 'wrap-around' ad in the Toronto Sun, which is not known for its support of New Democrat values, he added.

"I've got a lot of calls from New Democrats who are really upset at (her) trying to go after people I'd call working class Tories, the people who read the Toronto Sun," said Jacek. "I see New Democrats asking 'Why the hell is she advertising in the Toronto Sun?' That's a right-wing, neo-conservative, populist newspaper, so that's confused a lot of traditional New Democrats."

Horwath's decision to trigger an election also did not sit well with some union leaders, who considered the Liberal budget very labour and NDP friendly.

The Liberals clearly designed the budget to force the NDP's hand, said Wiseman.

"My assessment is the Liberals were determined to have an election ... and introduced an NDP-friendly budget to put the NDP's back up against the wall," he said.

Horwath also faced criticism early in the campaign for appearing wooden during her announcements, frequently using a tele-prompter to make sure she didn't stray from her prepared remarks.

She gained more confidence as the campaign progressed, and by the time the NDP released their platform May 22, Horwath spoke mostly off the cuff, using only some notes for support as she dropped jokes and one-liners while pacing back and forth in front of her audience and the TV cameras.

The political analysts said the NDP needs to work quickly to try and convince traditional New Democrats -- especially powerful labour leaders -- that Horwath is not abandoning the party's core values to try and get elected.

"Wynne had a lot of things in the budget that union leaders liked, and they're worried about (Progressive Conservative Leader Tim) Hudak and his pledge to cut public sector workers, and in a sense it's getting late in the day for Andrea at this point," said Jacek.

Wiseman also questioned whether the NDP can get the unions back onside in time for election day.

"My sense is that the NDP might very well lose seats compared to the last election, or to where they're sitting right now in the legislature," he said. "The unions are now lining up behind the Liberals."

Wiseman also wondered why Horwath waited nearly three weeks into the campaign to release the NDP's platform, which mirrored the Liberal budget in many areas, including transit funding, a caregiver tax credit and promises of a cut in auto insurance rates.

"Hudak's been campaigning for years ... and the Liberals have been setting the stage," he said. "The NDP were very late off the mark."

Jacek feels Horwath made a mistake when she started following Hudak's lead in question period this spring by attacking the Liberals over the cancellation of two gas plants and other scandals instead of focusing on the needs of ordinary voters.

"She started going into the scandals, and they're really a Tim Hudak issue, not an NDP issue," he said. "She essentially changed strategy this year and I don't think it's worked out the way they thought it would work out."

Another challenge for the New Democrats will be convincing people not to adopt so-called strategic voting -- voting for the Liberals to block the Conservatives from forming the next government. But Horwath's claim she triggered the election because the Liberals can't be trusted isn't winning over everyone, said Wiseman.

"A problem with the NDP's message in this campaign is it's saying that you can't count on what the Liberals are promising," he said. "Well, the rhetorical question is: what's changed in the past year? How come you supported them a year ago on the budget? Didn't all those things apply then?"

It'll also be hard for Horwath to be heard as the Liberals and Tories battle over Hudak's headline-grabbing plan to cut 100,000 public sector jobs to help balance the budget by 2016, a year earlier than the two other parties, said Jacek.

"The Liberals are going to keep saying that's the wrong way to go, while Hudak believes it's the right way to go, and that basically just squeezes out the NDP, and there's not much she can do about it at this point," he said.

The NDP should focus on helping the people who need it most, said Jacek.

"If I were advising her, I'd say emphasize that you have the best policy and strongest policy of all three parties on minimum wage," he said. "That has a lot of traction with a lot of people."

Both Jacek and Wiseman said Horwath needs to come up with a strong performance in the June 3 leaders' debate after getting off to a "rough start" in the campaign.

"Andrea Horwath may come across as the superstar in the debate," said Wiseman. "That could swing things."

-- with files from Will Campbell