og -18 的一句话

In the Pullman contest Randolph faced formidable

obstacles. The first was Black workers’ understandable

skepticism toward unions, which had historically barred

Black workers from membership. An additional obstacle

was the union that Pullman itself had formed, which

weakened support among Black workers for an

independent entity.

本句话到底是什莫结构？怎样分析这个weaken 和support的关系。谁weaken了谁，谁又support了谁？

谢谢解答！！