There's an old joke about federal politics that goes something like this: Conservatives go to party conventions to get drunk, Liberals to get lucky and New Democrats to debate the minutiae of dust-dry policy resolutions.

Fun-starved New Democrats will need their reputed love of policy to wade through the mountains of policy pronouncements being churned out by the seven contenders vying for the NDP leadership. But if they have the patience to scrutinize them closely, they'll glean some important differences about the candidates' priorities, style of leadership and approach to fiscal responsibility.

On the surface, there is, as British Columbia MP Nathan Cullen has so aptly put it, "violent agreement" on most issues.

No one is advocating a radical departure from the script laid out in the party's election platform last May by Jack Layton, whose untimely death in August triggered the current contest. That platform promised spending of almost $70 billion over four years on what Layton termed the real priorities of average Canadian families: things like health care, education, child care, elder care, retirement security, job creation and protecting the environment.

And it promised to do it all while simultaneously putting the country's books back in the black by rolling back corporate tax cuts, ending fossil-fuel subsidies, closing offshore tax havens, putting a price on carbon and dispensing with Prime Minister Stephen Harper's prison-expanding, tough-on-crime agenda.

For the most part, Layton's would-be successors haven't deviated from the broad themes of the platform, although some are promising to add to it or to tweak the odd proposal here and there.

Still, there are significant distinctions among the candidates in terms of the issues they've chosen to address, the number of promises they've made and the amount of detail they're prepared to provide.

For sheer volume, no one can beat Ottawa MP Paul Dewar. He's produced platform planks on everything from freshwater resources to foreign affairs, compiling almost four dozen specific promises -- and that's counting only the ones that carry a price tag.

He's promised to expand Employment Insurance to cover non-traditional workers; create a permanent, national infrastructure program; take the first step toward creation of a guaranteed annual income; boost foreign aid; provide tax incentives for small and medium-sized businesses to create jobs; invest in renewable energy; set aside another one cent per litre of the federal gas tax for municipal infrastructure; and provide "sustained, increased funding" for the CBC, the Canada Council and the Canadian Media Fund.

He's vowed to create a slew of special funds for women's shelters, home retrofits and women entrepreneurs, among other things. He's even promised a tax credit for fertility treatments.

Some of Dewar's proposals have been intricately detailed and costed, such as his $1.3-billion youth opportunities strategy or his $10-million plan to reinstate the per-vote subsidy, tied to each party's performance in recruiting female candidates. Others have been more vague but he's working with Informetrica's Mike McCracken and other economists to produce a fully costed platform before the campaign wraps with the final leadership vote on March 24, including spelling out how he'd pay for it all.

Dewar campaign spokesman Joe Cressy states the obvious: "Paul likes policy a lot."

"For those of us who are not wonks, we suffer endlessly through Paul's desire to talk and consult and discuss more policy."

Cressy says Dewar's strategy of papering the contest with his ideas is driven by his personal interest and his belief that discussion of policy is the way to engage people, draw them in. Moreover, Dewar believes party members are entitled to know what he'd do should he be chosen leader.

"Paul's approach has always been ... he's going to be upfront from the outset about who he is, what type of leader he is."

Toronto MP Peggy Nash has adopted a similar approach, churning out several dozen proposals. She's promising to invest in affordable housing, elder care and pharmacare; to expand EI; boost the Guarantee Income Supplement; create a 10-year national transit strategy; and ensure broadband Internet access in remote corners of the country. She'd create a new Canada Development Bank and introduce tax incentives for companies to create jobs, purchase high-tech equipment or invest in research and development.

"We believe it is necessary to release concrete policy proposals so that our members can make the most informed decision," says Nash campaign spokeswoman Zuzia Danielski. "It helps demonstrate the depth of candidates in various policy areas but also showcases the practical ideas that the NDP is offering to Canadians overall."

That said, Nash has deliberately shied away from getting into specific details on most of her proposals and she's provided few cost estimates.

"It is not possible to release a costing document during the leadership race," Danielski says. "The scope of the policies we've proposed depend largely on the state of government finances and the economy in 2015 (the time of the next election). Any specific numbers at this point would be speculative."

As to how she'd pay for her promises, Danielski says Nash would end subsidies to the non-renewable energy sector, eliminate tax loopholes and tax havens and review corporate tax rates. Some proposals -- like child care and infrastructure investments -- would pay for themselves by creating jobs and generating revenue for the government, she argues.

In contrast to Dewar and Nash, all the other contenders have produced a handful of proposals on a much narrower range of issues, a strategy they maintain is more fiscally responsible.

Indeed, former party president Brian Topp has made fiscal responsibility the centrepiece of his campaign, focusing on how an NDP government would generate the revenue needed to pay for all the good things it wants to do. He's proposed a detailed series of tax reforms to make the rich pay more, including hiking the corporate tax rate to 22 per cent from 15 per cent and creating a new 35 per cent tax bracket for individuals earning incomes of more than $250,000.

His strategy is based on the belief that the NDP won't make the next big step into government unless it can persuade voters it can be fiscally prudent.

"If you want to be trusted with a mandate, you have to show you're competent to govern," says Topp, who stresses his own record working as deputy chief of staff to former Saskatchewan premier Roy Romanow.

"Issuing lists of spending promises is one of the easiest things an opposition politician can do. And I have called on my colleagues to show how they are going to pay for their promises. It is something we all must do because you learn, in government, that the hard work of government is finding the resources to get things done."

That said, Topp has made a few promises of his own, including "substantial, sustained" funding for the CBC; creation of a cultural industries investment fund and a national nutrition program; and funding for home care, pharmacare, a national infrastructure program, post-secondary education and job training.

Montreal MP Thomas Mulcair has made three major, detailed policy proposals so far -- to set up a cap-and-trade system for all major greenhouse gas emitters, reform the public pension system and promote equality for women. Campaign director Raoul Gebert says there are "very few costs" attached to any of them. Indeed, cap and trade would eventually generate revenues, although Gebert acknowledges there would be an inevitable time lag before the money started flowing.

"(Mulcair) strongly believes that most Canadians share the NDP's goals and values and we must show Canadians we are capable of providing good, competent public administration before we will be elected to govern."

Gebert suggests there's no need for candidates to go overboard with new policy proposals, given that they're all building on the "strong foundation" shaped by Layton. Still, he says "it is important for leadership candidates to demonstrate the ideas and priorities they would bring to the table under their own mandate."

Cullen has been similarly parsimonious with policy pronouncements. Among other things, he's called for low or interest-free loans for retrofitting businesses and homes, a national public transit strategy and promised to work toward the goal of setting up high-speed rail corridors and development of an East-West power grid.

"We are resisting the temptation to come up with a policy for every question that comes forward," Cullen says. "I think that's a criticism of New Democrats, that we've never seen a problem that we didn't think a government program could fix."

He says it's critical for the NDP to be tightly focused on priority areas that are rigorously costed and affordable. Without that discipline, Cullen says the party could fall victim to the problem that plagued former Liberal prime minister Paul Martin, who was dubbed "Mr. Dithers," someone widely perceived as having so many priorities that nothing was a priority.

"If (New Democrats) are looking for the shopping list of every issue under the sun that we're going to tackle all at the same time, they should vote for somebody else," says Cullen. "I don't think that's the way the world works."

Nova Scotia pharmacist Martin Singh echoes that view. He's produced weighty papers on the environment, health care and entrepreneurship. He's provided a particularly detailed proposal for a national pharmacare program, which he says would ultimately save the federal treasury $5.5 billion.

"There's two different approaches: You can have your one-pager on everything or you can grab three or four solid ideas and go very deep into them," Singh says.

For Manitoba MP Niki Ashton, sticking to a few, fairly general promises -- including the novel notion of creating a Crown corporation to produce generic drugs -- is not simply a matter of being focused or fiscally prudent. She believes it's not up to a leader to impose policy from the top down; it's up to rank and file New Democrats to provide bottom-up direction on where their party should be headed.

"That's a fundamental tenet to the NDP and why we are different than the other parties. There is a real respect for the grassroots," she says.

New Democrats will have to decide whose priorities and policy approach they prefer. But as they ponder their decision, they should be aware that Harper's Tories are keeping tabs on all the promises and are already honing their line of attack.

Tory party spokesman Fred DeLorey sums it up: "While our Conservative government is focused on Canadians' top priority -- jobs and economic growth -- the NDP wants to hike taxes that would kill Canadian jobs and engage in massive deficit spending that would cripple Canada now and into the future."