The decision to award race drama 12 Years a Slave the 2014 Oscar for best film was unpopular among supporters of America's Republican party, according to a new study.

Only 15% of participants who identified as Republican voters said they felt the Academy of Motion Picture Arts and Sciences had made the right choice for the annual awards ceremony's top prize. The figure compared to 53% of Democratic party supporters who said Steve McQueen's slavery biopic, which also won best adapted screenplay (for John Ridley) and best supporting actress (for Lupita Nyong'o), deserved its success. Overall, 52% of respondents told Public Policy Polling they were not sure which film should have won.

The survey of 1,152 registered voters, which was carried out online and via the telephone, suggests attitudes towards 12 Years a Slave's harrowing depiction of the realities of slavery in the antebellum deep south are divided sharply on political lines.

12 Years a Slave was not feted by the Obama administration in the run up to the Oscars. The president chose instead to praise another film with a civil rights theme, Lee Daniels' The Butler. A White House screening was also staged for the Nelson Mandela biopic Mandela: Long Walk to Freedom.

• 12 Years a Slave: could only a Brit really have made it?