TORONTO — Canadians have an obligation to keep their "moral promise" to Afghans despite a mounting death toll, Liberal leadership contender Michael Ignatieff said Wednesday as the bodies of five more soldiers returned home from the battlefield.

"This is an agonizing mission for Canadians but it's a mission that amounts to a moral promise," Ignatieff said following a rally in downtown Toronto where he unveiled a new campaign platform.

"It's a promise in which Canada said `We're going to help Afghans get their country back on its feet.' And the Canada I love and the Canada I respect always keeps its promises."

The latest casualties in Afghanistan, which brings the total to 32 since 2002, have prompted a growing number of politicians to push for an end to the mission.

Earlier this week New Democratic Party Leader Jack Layton said Canada should pull forces out and focus its efforts on reconstruction and negotiating a peaceful settlement.

Ignatieff dismissed Layton's proposal, saying it wasn't credible.

"I'm not clear who you negotiate with. I'm not clear what you negotiate about," he said.

"There isn't a responsible politician who doesn't prefer negotiating to combat. That's not the issue."

Ignatieff said he would continue to back soldiers so long as the mission offered the war-torn country a balance of security, reconstruction and humanitarian needs.

He made the comments following a rally where he kicked his fight for the top Liberal job into high gear unveiling an Andy Warhol-inspired poster campaign and a 40-page "nation building" manifesto.

He said it's time Canada's political leaders work to unite the rural and urban parts of the country. "This vision is anchored in the deepest traditions of our party," he said.

Ignatieff's "Agenda for Nation Building" includes a plan for a consolidated financial aid program for students to improve access to post-secondary education.

To tackle climate change, Ignatieff proposes tax incentives for using clean fuels and higher emission standards for cars.

The former academic said that the Liberals need to be strong, bold leaders because the country is tired of being "manipulated" by Stephen Harper's Conservatives.

Ignatieff's is the latest in a series of rallies being held this week and next by the 10 Liberal leadership hopefuls as they scurry to secure support ahead of the December leadership convention.

Ignatieff rival Bob Rae plans to unveil details of his platform on health policy and federalism over the next few days.

Ken Dryden got the ball rolling earlier this week launching his `big Canada' document. Stephane Dion, meanwhile, released a detailed plan for meeting Canada's climate change targets and making Canadians more energy efficient.