The governing Conservatives introduced the changes last spring and they are slated to take effect in 2023. The government says the measures will help ensure the sustainability of the pension system.
Speaking at a town hall meeting sponsored by the seniors' organization CARP, Mulcair said the NDP would kill the changes within its first year of forming a government.
"We honestly believe that in a country as wealthy as Canada it is absolutely inexcusable to have hundreds of thousands of seniors living below the poverty line, and an NDP government will correct that immediately in its first year," Mulcair said.
He said he'd also strengthen the Canada Pension Plan and the Quebec Pension Plan, and ensure that seniors with workplace pensions are protected if a company goes bankrupt.
"We're one of the only countries that doesn't protect pensions in the case of bankruptcy or insolvency," said Mulcair. "That's entirely unacceptable."
Mulcair added that the NDP would also propose a caregiver tax credit for seniors who take care of their spouses, which would take some pressure off an already taxed health-care system.
CARP recently came under attack at the Commons finance committee from Conservative MP Paul Callandra, who suggested the organization had a pro-Liberal partisan bias. The group has come out this year against the changes to Old Age Security.
Mulcair suggested Prime Minister Stephen Harper felt the same way as Callandra.
"Mr. Harper uses messengers like Mr. Callandra all the time to deliver his contempt for anyone who dares disagree," Mulcair said.
"In Mr. Harper's Canada, independent voices are to be discredited, in Mr. Harper's Canada, well-connected insiders get ahead while the rest of us are left to fend for ourselves."
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