party man

a person belonging to a political party, especially one who adheres strictly or blindly to its principles and policies.

Origin of party man

First recorded in 1685–95

Ask not him to make a statesman a party-man, or the churches an apology for his lowness.

Speeches, Addresses, and Occasional Sermons, Volume 1 (of 3) |Theodore Parker
But the Irish lord-lieutenant is always a party-man, and is always surrounded by party-men.

The Land-War In Ireland (1870) |James Godkin
Likewise, that the Author is no Party-man, but a general Meddler.

Benjamin Franklin |Frank Luther Mott
The question whether and to what extent the poet ought to be a party-man is a very complex one.

Main Currents in Nineteenth Century Literature - 6. Young Germany |Georg Brandes

party man

a loyal member of a political party, esp one who is extremely loyal or devoted