Rivera did not agree with principal Rockefeller Center architect Raymond Hood's suggestion that the mural be commissioned exclusively in grayscale colors. Rivera also declined to take part in an artistic competition prior to the announcement of his commission, and he wanted to withdraw from the project when it was announced that neither Matisse nor Picasso would be painting at the RCA Building. He eventually acquiesced after Nelson convinced Hood to remove his grayscale requirement and allowed Rivera to paint "Man at the Crossroads" in a fresco format. However, Rivera withdrew again after Sert and Brangwyn were announced as the new artists, calling them "two inferior painters". He eventually rejoined the project by fall 1932.