Progressive Social Democratic Party of the Republic of New England
Founded 1986
Preceded by Socialist Party of the United States
Ideology Social democracy, nationalism, Democratic Socialism, liberalism, progressivism
Political position Center-Left
International affiliation Socialist International
Official colours red, green
The Progressive Social Democratic Party of the Republic of New England (often called the PSDP and occasionally called the Progressives, the Democrats, the Social Democrats and/or the Socialists) is a center-left political party, and the most successful in the nation's brief history. It has had three of the RNE's six presidents (Milton Emerson, Jr., Bernie Sanders and Howard Dean) and has never been out of majority in parliament, as the two Prime Ministers of the RNE (Ted Kennedy and John Kerry) were both members of the PSDP. It also holds a majority of state governorships, five out of seven (Libby Mitchell in Maine, John Lynch in New Hampshire, Deval Patrick in Massachusetts, Dan Malloy in Connecticut and Peter Shumlin in Vermont), and is considered among the most successful upstart left wing parties in the world. It's President, Pat LaMarche, sits on the board of directors for Socialist International.

There has never been a Prime Minister of the RNE that hasn't been a member of the PSDP. Ted Kennedy, who was Prime Minister from 1986 until his death in 2009, was a founding member of the PSDP. The current Prime Minister is John Kerry, also of the PSDP.

It is seen as a center-left party, but significantly further left than the Socialist Party of the United States, as a result of the left-wing politics of the Republic of New England.

Many ideologies are found in the PSDP. From market liberalism to progressivism to social democracy to socialism, the PSDP is seen as a big tent party for anyone left-leaning. Among the non-negotiable core facets of the PSDP, however, are its stance on civil rights. Any member of the PSDP must pledge to support equal rights for all people, regardless of race, gender, sexual orientation or religion, one of the few parties in the world that takes such a broad stance on behalf of all of it's members in civil and human rights.