partisan
par-ti-san
noun
A strong, often uncritical, supporter of a person, group, or cause.
"She was a partisan of the new policy."
adjective
Showing strong, often biased, support for a particular party, cause, or person.
"His analysis was clearly partisan."
Thesaurus
Synonyms: partizan, drumbeater, zealot, enthusiast, tendentious, tendencious, party-spirited
Antonyms: nonpartisan, nonpartizan