LOS ANGELES (Reuters) - Making a film about an iconic politician like Britain’s Margaret Thatcher is akin to walking into a movie minefield, and casting an American — even one as revered as Meryl Streep — is asking for more trouble.

Yet the makers of new movie “The Iron Lady,” which opens in US theaters on Friday, went one step further.

They chose to depict Thatcher, now 86, as a confused, lonely woman looking back on past glories, and doing so takes the kind of guts once exhibited by the former British prime minister herself.

British director Phyllida Lloyd and screenwriter Abi Morgan said they never set out to make an historical biopic or a film about politics. They wanted to tell the story of a woman of ordinary origins who rose to great power only to fall back again into a normal, elderly life that is much like anyone’s.

“It is a Shakespearean story about power and loss, and the cost of a huge life, and letting go,” Lloyd told Reuters.

“The Iron Lady” is the first feature film about Thatcher, Britain’s only female prime minister who was elected in 1979 and forced, in tears, out of office in 1990 after losing the support of her cabinet.

Thatcher, a Conservative, was revered for uncompromising opposition to the Soviet Union and for putting the “Great” back in Great Britain. But she also was reviled by labor unions and blamed for creating deep divisions in British society.

Lloyd said there has been “astonishingly little backlash” in Britain about casting American Streep to play the British icon. Moreover, the role required portraying a woman in the prime of her life and in decline, and that sort of contrast meant a skilled actress who understood the nuances of both.

“You needed someone of the magnitude of Meryl Streep to take on Margaret Thatcher’s size and personality. You needed a superstar to play a superstar,” Lloyd said.

The casting appears to have worked. Streep, a master of theatrical manipulation, has received an armful of awards for her performance and is tipped to get her 17th Oscar nomination when Academy Award nominees are announced in January.

But Streep and the filmmakers wanted to do more than a movie biography of Thatcher and her politics .