From way back when I own the German translation of The Ides of March, and a few years ago I acquired a used copy of the original novel which turned out to be the 1948 edition.
In the book there is an undated leaflet simply labeled "Printed in U.S.A.," containing a review called "A Report by Clifton Fadiman" (Wikipedia biography, handle with care) and "Thornton Niven Wilder" by Rosemary C. Benét, wife of Stephen Vincent Benét. Googling, I found her name frequently, and among other things she was a reviewer for The New Yorker. This may have been a Book of The Month Club leaflet. (Update: the novel was indeed the March 1948 Book of the Month Club selection.)
I scanned it the leaflet, and here it is: Download The-Ides-of-March-leaflet.pdf
I think the book review is really helpful for our chat, and it concludes with:
[this] is a book by an educated human being, sensitive to the weight and import of two thousand years of European tradition, unwilling to throw it aside in a fit of barbaric egoism, anxious to incorporate it into his work. To my mind, The Ides of March is one of the most truly civilized novels by an American I have read in some years.
Benét's biography is rather personal: Wilder was a friend of her husband from way back at Yale University. One of her comments is:
I remember once in a group, a general discussion boiled up about whether or not we would live our lives again if we had to do so without any change in pattern. Some of us were a little lukewarm at the idea, but Thornton spoke up in a way I never forgot and said categorically, "Life in itself is a gift."