I think that the Post Office mural movement that comes out of the New Deal carries with it significant political messages. Consider the words of Harry Hopkins, Roosevelt's relief administrator:
During this time government-created agencies supported the arts in unprecedented ways. As Harry Hopkins, Roosevelt's relief administrator said in response to criticism of federal support for the arts, '[artists] have got to eat just like other people."
This would be one of the dominant messages that come out of the Post Office Murals. The artist was seen as a part of society. When relief in the form of the New Deal was made open to society, it was also made open to the artist in the form of commissioning this New Deal example of art. At the same time, the post office representing an area where all people from all walks of life would be able to appreciate the art rendered helped to democratize art. This democratization helped to underscore President Roosevelt's premise that if all people work together towards advancement, the nation can find a level of liberation from the condition of economic and social challenge. At the same time, the message of the art depicted a particularly positive view of America, emphasizing American pastoralism or the "spirit" of what it means to be a triumphant American. This helped to amplify Roosevelt's desire for Americans to focus on the hope of the future, as opposed to the painful condition of the present.