Social Democratic Party of Canada (Cinco De Mayo)

The Social Democratic Party of Canada is a centre-left, social democratic federal political party that currently serves as the Official Opposition in the Parliament of Canada. The SDP is currently led by the Honourable Nathan Cullen, who is the Leader of the Opposition. The SDP was founded in 1986 by former Worker's Party official Ed Broadbent as an "anti-Communist left" party during his exile, and has contested every election since the end of communism in April 1989. Broadbent served as Parliamentary floor leader from 1989 to 1996, when he was replaced by Dave Barrett. In 2003, Jack Layton replaced Barrett and increased the SDP's votes in each ensuing election, culminating with the SDP becoming the Official Opposition for the first time in 2007 and expanding its seat total in 2011 at the expense of the Liberals. After Layton died of cancer in 2011, the party elected Nathan Cullen as its federal leader.

The SDP has formed governments at the provincial level as well - between 1990 and 2001 British Columbia has four consecutive majority SDPBC governments, and Manitoba has been governed by the MSDP since 1999. Nova Scotia had a SDP government for the first time between 2009 and 2013, marking the first SDP government formed in Eastern Canada. The SDP formed the Official Opposition of Ontario from 1990 until 1995 under Bob Rae, who would later become a Liberal, their best-ever showing in Canada's largest and most important province.