It's a cry not often heard in a federal Liberal stronghold but Gilles Derome delivers it with gusto.

"NPD, NPD,'' the 84-year-old says as he walks down the street toward a mainsteeting NDP Leader Jack Layton, using the French acronym for the New Democratic Party.

It's music to the ears of Layton and Thomas Mulcair, the former Quebec environment minister turned star NDP candidate for the Sept. 17 federal byelection in the Montreal-area Outremont riding.

But the enthusiasm might be short-lived. Even after some jovial glad-handing and chatter with Layton and Mulcair, Derome is still not sure how he's going to vote.

"My mind's not made up,'' the retired doctor said as the NDP chief, Mulcair and their entourage continued down a central Montreal boulevard. "Certainly not the Bloc.''

He knows the Liberals and has voted Conservative. Maybe he'll try the NDP.

"I'm thinking of them but I find them maybe a little too socialist. But they're certainly very good.''

Outremont is one of three Quebec byelections being held Sept. 17. The others are in rural St-Hyacinthe-Bagot and Roberval-Lac-St-Jean.

St-Hyacinthe-Bagot and Roberval-Lac-St-Jean were held by the Bloc Quebecois, although pundits have said they could go to the Tories. Outremont is a Liberal stronghold, previously held by Jean Lapierre.

The Conservatives are running former diplomat Gilles Duguay and the Bloc is fronting Jean-Paul Gilson, a psychologist, in Outremont.

But it's widely considered a two-way race between the Liberals and the NDP, which came in third behind Lapierre and the Bloc candidate in the last general election.

Mulcair, who also has a background in public administration, has as his main rival Jocelyn Coulon, an influential academic and political commentator. Coulon was hand-picked by Liberal Leader Stephane Dion to run in Outremont.

But Mulcair, 53, says Liberals dissatisfied with Dion are coming over to his camp and that adds to the importance of next month's vote.

"A byelection is an opportunity to send a message,'' he said. "For a lot of federal Liberals, that message is we're dissatisfied with Stephane Dion's weak leadership and a lot of them are very comfortable with us and the NDP.''

Winning Outremont would bring the NDP out of the political wilderness in Quebec, where the party hasn't held a seat since consumer advocate Phil Edmonston won a byelection in 1990.

It's also judgment day for the Liberals and Conservatives, says Layton.

"It's an effort that is very important to us because it's kind of a mid-term evaluation of whether Mr. Harper is taking the country in the right direction,'' he said.

"And people don't feel that positive really about what's happening with the Liberals under Dion. The leadership doesn't seem to be there.''

Mulcair's team was already campaigning about a month before the byelection was called and they peppered the riding with signs the night the vote was announced.

Tory and Bloc signs are outnumbered by Mulcair posters on a couple of main thoroughfares and Coulon's are nowhere to be seen in some spots.

"We think we've got a serious chance of taking the riding,'' Mulcair said.

Mulcair, who comes from a family of 10 children, was a member of the Quebec legislature between 1994 and 2007.

He quit cabinet in late 2006 when Premier Jean Charest wanted to move him from the environment portfolio where he had sparred with Charest over the privatization of part of a provincial park.

That project was later cancelled when Charest was re-elected with a minority government.

Mulcair, whose mother's great-grandfather was Quebec Premier Honore Mercier, said he shares the NDP's values and respects Layton.

He was less complimentary when it came to Dion, whose leadership he described as "incredibly weak.''

"Canada had the worst record of all the western countries with regard to greenhouse gas production under the Liberals, including Stephane Dion,'' he said.

Mulcair says Quebecers are giving the NDP another look because of its stand on Afghanistan and the environment.

Still, he says the NDP must make its policies better known in Quebec.

"When I look at our policies, for example, on agriculture and the environment, and I go into the ridings in the more rural areas, people are very pleased to find out what those policies are but they're simply not well known,'' he said.

"The message is starting to get through. Our polling numbers have been firming up month after month and are holding steady at a much higher rate than they have been here in the past. Key issues like Afghanistan are going to carry us through, I think, in a lot of ridings.''

Back on the street, two men sitting out in front of a store are divided on who they'll support.

"I am a Liberal and I'm going with the Liberals,'' said Mo Yazdani. "They are good, they bring the economy. They raise the prices of everything but they're still good.''

He's not troubled by concerns about Dion's leadership.

"For me, honestly, I'm thinking most of them are the same. They follow one program but only the name will be changed.''

His friend, who identified himself as Steve, said he's thinking of backing the NDP.

"I like the guys, better than anybody else,'' said the man, adding he used to be a Liberal. "I like to try the new guys. The new guys are more down to earth.''