party membership; party register
Refers to being registered as a member of a political party. Often used in phrases like 党籍を持つ (to hold party membership) or 党籍を離れる (to leave a party).
He holds membership in the Liberal Party.
He has held membership in the Liberal Democratic Party for many years.
He left the party and ran as an independent.
He left the party after the scandal came to light.
She had her party membership revoked due to the scandal.
After his apology, his party membership was restored.