我认为，这个句子在 than 之前漏掉了与之对应的某个“比较词”（由more 或 -er 构成），或者，把 than 改为?rather than，意思是“而不是”，以排除后者。即：And today, almost twice as many voters identify themselves as independents rather rather than as members of either the Democratic or Republican parties.1.?twice as many voters 后面省略了已知的比较项：as other people （指其他类别的人）。2.?identify themselves as independents：为 identify ... as ...“认为...是...”，as 部分作宾补。3. rather than：而不是4.?as members 与?as independents 是并列成分，由准并列连词 rather than 连接。And today, almost twice as many voters identify themselves as independents rather than as members of either the Democratic or Republican parties.【怎么翻译】如今，几乎两倍的选民认为自己是独立的选民，而不是民主党或共和党的成员。