Union leaders are fighting against the wage freeze.

Literal

Labor-union [possessive-の] executives [topic-は] wage-raise [possessive-の] freeze [against-に] opposing, fighting.

幹部 ('executives, leaders'). 賃上げの凍結 ('wage-raise freeze') stacks economic nouns. 闘う (たたかう) is the kanji used for social/political battles.