A noisy crowd of supporters greeted NDP Leader Tom Mulcair as he made his way to the podium in Halifax on Sunday.

It was Mulcair’s first campaign stop in the Maritimes, and he used the opportunity to tout his party’s plan to help the middle class.

“Clearly Stephen Harper's plan isn't working,” said Mulcair, “and his priorities are clearly out of step with the priorities of Nova Scotia.”

Mulcair reiterated earlier campaign promises to implement $15 a day childcare and $15 minimum wage.

Organizers say they expected about 500 people to be in attendance. More than 700 people were let in, however, as many as 100 were turned away at the door.

That left NDP supporter Robert Young wishing there had been better planning.

“They could have looked at when they realized how many people they had, even moving it outdoors,” he said.

But Mulcair had bigger questions to answer. A new Conservative attack ad was released Sunday questioning the NDP’s plan to balance the budget amid their spending promises.

“Mulcair’s either going to have to cut the spending that they've already proposed and committed to, or raise taxes, or both,” said Calgary Conservative candidate Jason Kenney. “It's a question of math, not of opinion."

The Conservatives say the NDP plan would leave an $8 billion hole.

“That’s not true,” said Mulcair. “That’s just something the Conservatives are making up.”

Less than an hour later, the Liberals accused Mulcair of being off by $28 billion over four years.

“Of all the platforms I’ve ever seen, this is the biggest, darkest, deepest black hole imaginable,” said Ontario Liberal candidate John McCallum.

Mulcair claims his spending is balanced by cuts to Conservative programs, such as income splitting.

“Whether it's $15 a day child care or any other undertaking we've put forward, we've always explained exactly how much it was going to cost. We've said every step of the way what changes we would make on the revenue side,” he said.

Mulcair is the second federal leader to visit Nova Scotia during the campaign. Conservative Leader Stephen Harper made a stop in Amherst on Aug. 16.

Green Party Leader Elizabeth May will be in Halifax on Monday.

Fifty days remain on the campaign trail before the Oct. 19 election.

With files from CTV Atlantic’s Sarah Ritchie