Complex sentence: Gompers, like most labor leaders of his era, opposed unrestricted immigration from Europe because it lowered wages and opposed all immigration from Asia because it lowered wages and represented, in his judgement, an alien culture that could not be easily assimilated.
Split into simpler sentences: Gompers, like most labor leaders, opposed unrestricted immigration from Europe because it lowered wages and opposed. He strongly opposed all immigration from Asia because it lowered wages and represented, in his judgement, an alien culture that could not be easily assimilated.