这个句子的翻译是错误的，原因是对定语从句结构分析错误。

cellar：the lowest grade or rank 《韦氏》

lift sth from the cellar：使...摆脱困境

consign sb to sth.: to put somebody/something in an unpleasant situation

The decision to close the factory has consigned 6 000 people to the scrapheap.

A car accident consigned him to a wheelchair for the rest of his life.

which = the cellar

it = Grant's presidency

And a similar process is lifting Grant's presidency from the cellar （先行词）to which an unholy alliance of neo-Confederates and genteel reformers had consigned it. （定语从句）

一个类似的过程即将使格兰特的当政时期从新联盟者和上流社会改革者共同使之陷入的困境中摆脱出来。