An American politician says he will challenge the results of a local election because he believes the man who beat him is dead and being represented by a body double or robot. 

In a letter posted on his personal website, Timothy Ray Murray claims Frank D. Lucas, who beat him on Tuesday to be the Republican nominee for an Oklahoma congressional election, has been dead for three years.

"It is widely known Rep. Frank D. Lucas is no longer alive and has been displayed by a look-alike," he said.

Mr Murray further claimed there was evidence to show his opponent was executed in Ukraine after being sentenced by an organisation he called the "world court".

Mr Murray was soundly beaten by Mr Lucas in the contest for Oklahoma's third district. Mr Murray received 5.2 per cent of the vote and Mr Lucas 82.8 per cent.

Mr Lucas has been a congressman for more than 20 years. He told a local news show he had never even been to Ukraine.

"It does come as kind of a shock to read that you're not you," Mr Lucas said. "Many things have been said about me, said to me in the course of all my campaigns. This is the first time I've ever been accused of being a body double or a robot."

Mr Murray alleges this is not the first time a congressional race has been won by a non-living person.

"This is a situation similar to the senators from Kentucky situation in the 2012 election," he said.