strongly supporting a particular person or cause
partisan - biased
If you are called ‘partisan’, then you are considered to be completely devoted to your own particular political party, ideology, leader, etc., at the expense of all other alternatives. In most cases, the word is used negatively as it implies a lack of careful thought or moral principles and a blind prejudice. However, it is considered a positive when it comes to supporting your favourite sports team.
That political candidate is receiving hugely partisan support from the media who are covering for all his errors.
The match was played in front of a partisan crowd who cheered their team to victory.
The important bill was blocked at the last minute by the opposition, in what was a blatant act of political partisanship.