ruling coalition party
Refers to a political party that is part of the ruling coalition government. Used in news and political contexts.
The ruling coalition party announced a new policy.
与党 means 'ruling party' in general, while 連立与党 specifically refers to a party within a ruling coalition.
連立政権 is the coalition government itself, whereas 連立与党 refers to the individual parties that make up that government.
Compound of 連立 (coalition) and 与党 (ruling party).