#JavaScript (ES6), <s>231</s> <s>227</s> <s>223</s> 221 bytes

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    _=>`First${t=" they came for "}the Socialist${a=`s, and I did not speak out-
    Because I was not a `}Socialist${t=`.
    
    Then`+t}the ${(u="Trade Unionist")+a+u+t}the Jew${a}Jew${t}me-and there was no one left to speak for me.`

---
##Try it

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    o.innerText=(
    _=>`First${t=" they came for "}the Socialist${a=`,s and I did not speak out-
    Because I was not a `}Socialist${t=`.

    Then`+t}the ${(u="Trade Unionist")+a+u+t}the Jew${a}Jew${t}me-and there was no one left to speak for me.`
    )()

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    <pre id=o>

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