Norman Rockwell's Which One? (Undecided Voter) achieved $6.5m at Sotheby's American Art sale on November 21.

The piece dates to 1944 and references the tight presidential race between Democratic incumbent Franklin D Roosevelt and his Republican challenger Thomas E Dewey.

Rockwell's Which One was used as the cover of a 1944 edition of the Saturday Evening Post

Like most of Rockwell's most memorable works, it was used as the cover to an edition of the Saturday Evening Post.

Rockwell's work has become increasingly valuable in recent years; he posted a string of record sales in 2013.

His masterpiece, Saying Grace, made $46m that year.

Liz Sterling, head of Sotheby's American art department, said: "We were particularly delighted… to introduce Norman Rockwell's Which One? to auction for the first time. "

"The election-themed painting now ranks among the top auction prices achieved for the artist."

Gray Day (1935-1937), a work by the modernist painter Rockwell Kent, sold for $852,200 - setting a new record for the artist at auction.

Kent was a keen explorer and transcendentalist who travelled widely in the world's most remote wildernesses.

He spent many years living in Alaska, Tierra del Fuego and Greenland - where he produced this work.

While Kent is perhaps best known for his distinctive woodcut illustrations, which were published widely, his powerful landscape paintings have a strong following.  

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