Alexa McDonough is endorsing Peggy Nash for the party's leadership.
The former federal NDP leader says the Toronto MP has the skills and experience to take on what she described as the Conservative government's failing economic policies.
In a statement, Ms. McDonough says Ms. Nash also has the activist roots to continue building the party throughout the country.
Ms. McDonough served as the leader of the federal NDP from 1995 to 2003 and led Nova Scotia's New Democrats from 1980 to 1994.
So far, there are nine candidates in the race to succeed Jack Layton, who died earlier this year after a battle with cancer.