The Republican Party in Texas has said it is "shocking" and "disturbing" that a TV drama is to depict the assassination of US President Bush.
Death of a President uses archive footage, actors and computer effects to portray the president being shot dead.
UK broadcaster Channel 4, who made the mock documentary, said it explored the effects of the War on Terror on the US.
But Gretchen Essell, a spokeswoman for the Republican Party of Texas, called for it not to be screened.
"I cannot support a video that would dramatise the assassination of our president, real or imagined," she told the Press Association news agency.
"The greater reality is that terrorism still exists in our world. It is obvious that the war on terror is not over.
"I find this shocking, I find it disturbing. I don't know if there are many people in America who would want to watch something like that."
The 90-minute film shows Mr Bush being targeted by a sniper during anti-war rally in Chicago in 2007.
He is confronted by a demonstration when he arrives in the city to deliver a speech to business leaders and is shot as he leaves the venue.
The ensuing investigation focuses on a Syrian-born man.
A White House spokesman said of the programme: "We are not going to comment because it does not dignify a response."
The drama will have its world premiere at next month's Toronto Film Festival before a screening on UK digital channel More4.
John Beyer of UK TV pressure group MediaWatch said the film was "irresponsible".
He said it could even trigger a real assassination attempt and told the Daily Mirror: "There's a lot of feeling against President Bush and this may well put ideas into people's heads."
Peter Dale, head of More4, described it as a "thought-provoking critique" of contemporary US society.
He said: "It's an extraordinarily gripping and powerful piece of work, a drama constructed like a documentary that looks back at the assassination of George Bush as the starting point for a very gripping detective story.
"It's a pointed political examination of what the War on Terror did to the American body politic.
"I'm sure that there will be people who will be upset by it but when you watch it you realise what a sophisticated piece of work it is.
"It's not sensationalist or simplistic but a very thought-provoking, powerful drama. I hope people will see that the intention behind it is good."
Producers of the film, which is directed by Gabriel Range, hope to sell the broadcast rights to the US.
Death of a President will be shown on More4 on 9 October.