Here's what I received from the FDR Library:
Dear Mr. Brennan:
This is in response to your e-mail of December 19, 2012 regarding a large, framed image of Franklin D. Roosevelt you have.
From the photo links you provided I am unable to tell whether the image is an original painting or not. If you do not see any brush strokes, it is possible that it is an illustration printed on canvas with a varnished surface (which may be what accounts for the surface cracking). With a in-person examination of your piece, a reputable antique dealer or artwork appraiser in you area should be able to quickly inform you as to whether or not it is an original painting or print.
A search of our Museum collection found no identical portraits of FDR. Our collection does have, however, numerous paintings, drawings, illustrations, etc. of FDR very similarly posed. It was fairly common during FDR's presidency for artists - both professional and amateur - to be inspired by photographic images of FDR. I believe this to be one of those cases. Judging by the dates of the other similar pieces, it is likely that the inspiration was a 1933 photo of President Roosevelt.
Your piece may have just been done simply as a tribute piece, or perhaps as a campaign piece. There does not appear to be any indication as to which is the case. If done as campaign piece, it was likely created for the 1936 campaign for which similar portraits of FDR show up on campaign memorabilia.
Best wishes,
Michelle M. Frauenberger
Museum Collections Manager
Franklin D. Roosevelt Presidential Library
4079 Albany Post Road Hyde Park, NY 12538