What is the Independent Party?
http://www.indparty.com/
Oregon has closed primaries, too.
http://sos.oregon.gov/voting/Pages/voteinor.aspx#politicalparties
http://indparty.com/platform
I can’t say it’s necessarily liberal.
Apparently they have enough registered voters to be a “major” party - but no office holders in the U.S. Congress, the state legislature, or the state row offices.