Republican congressional candidate Samuel Wurzelbacher has claimed that gun control by Nazi Germany contributed to the Holocaust because the victims did not have firearms to defend themselves.
In a short campaign video shows the Ohio candidate, who is also known as "Joe the Plumber" for his alleged everyman views, loading his shotgun and shooting at lemon and tomato targets on wooden posts.
The video narration says: "In 1939, Germany established gun control. From 1939 to 1945, six million Jews and seven million others, unable to defend themselves, were exterminated."
Wurzelbacher then turns to the camera and declares: "I love America."
The video has outraged Democrats and several Jewish organisations.
He also posted the video on his Facebook page with the description: "The 2nd Amendment essentiality protects our rights as Americans. Watch the video and find out why."
"Using the memories of the six million Jews killed in the Holocaust to make a political point is never appropriate under any circumstances," said David Harris, president of the National Jewish Democratic Council.
He urged Wurzelbacher: "Apologise and remove this offensive video immediately."
Chris Redfern, the Ohio Democratic party chairman, described the video as "incredibly offensive".
But Wurzelbacher defended his action and tweeted: "No one in the video said gun control caused genocide."
Gun control opponents have long maintained that controls on firearms partially helped Adolf Hitler to seize power in Germany.
Wurzelbacher rose to fame when he questioned Barack Obama on his small business tax policy at an event in Ohio during the 2008 presidential election.