A film about the killing of Osama bin Laden which will air two nights before the US presidential election has been re-edited to feature more footage of Barack Obama, prompting accusations Hollywood is trying to swing the vote.

Harvey Weinstein, a studio head and prominent Democrat who has contributed to the president's campaign, tweaked the film, Seal Team Six: The Raid on Osama bin Laden, to broaden Obama's role.

The new version of the 90-minute feature, which will debut in primetime on 4 November on the National Geographic Channel, and be available the next day on Nextflix, uses additional news and documentary footage to show Obama in the build-up and aftermath of the May 2011 raid which killed the al-Qaida leader in Pakistan.

Weinstein and the director, John Stockwell, told the New York Times the changes, instigated by Weinstein, were motivated not by politics but to imbue more realism.

The footage includes the president speaking at the annual White House correspondents' dinner a day before the raid, a lonely walk in which he appears deep in thought, and a triumphant declaration – "Justice has been done" – after the raid.

The extra footage was shot by Meghan O'Hara, a producer who collaborated with Michael Moore on the George Bush-bashing documentary Fahrenheit 9/11.

Conservatives were angry about the film and its timing even before the re-edit, calling the Weinstein Company and Voltage Pictures production a blatant attempt to influence voters.

News of the new, Obama-expanded version ratcheted up resentment on blogs and website talkboards on Wednesday.

"It's a propaganda film from start to finish," said one commentator. "I wonder if Obama is going to have a starring role and jump out of the helicopter," asked another. Several lamented what they called Hollywood's liberal bias.

"It is amazing, Hollywood actually believe what their big, fat hyper-inflated egos tell them – that we the people are stupid and they can do anything they want. Time to fire these 'entertainers' by NOT watching their movies or television shows."

It could, from a Republican perspective, been even worse. An earlier version of the film included a scene in which Mitt Romney appeared to oppose the raid.

Howard T Owens, the chief executive of the National Geographic Channel, told the Times his company demanded that scene be cut. "We wouldn't air this if it were propaganda."

The film's timing, he said, was to take advantage of the fall schedule of TV shows. Another motivation was desire to get in ahead of the Zero Dark Thirty, a bigger budget film about the raid directed by Oscar-winner Kathryn Bigelow.

"Other than being commercially opportunistic, we weren't considering the election," said Owens.

Zero Dark Thirty was originally slated to appear in cinemas before the election but was pushed back to December amid complaints it could unfairly boost Obama. Republicans also accused the White House of sharing classified information with Bigelow and her writer-producer, Mark Boal.

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