I have to use a majority of primary sources and I'm concerned that I may be lacking in that department as well. I'm just curious if anyone has some insight and could possibly lead me in the right direction on where I could start looking and if this essay topic is possible. Thank you!!!
It is certainly possible to do. I guess my question would be do you think you are actually going to be doing anything new or interesting? There has to be something a bit more nuanced to your argument than "they decided to do nothing" if you are working on a 20 page research paper.
So when it comes to western knowledge of the Holocaust, the biggest two primary sources are Riegner Telegram, which informed the UK government of the Holocaust, and this pamphlet produced by the Polish Government in Exile, which described the Holocaust based on the testimony of Jan Karski.
Looking around, I can find references to a state department memo acknowledging that the stories of the Holocaust were likely true, and a Gallup Poll where 47% of Americans believed that millions of Jews had been killed, both from 1943. Unfortunately I haven't been able to find the original source for either, but you may have better luck.