US action hero Arnold Schwarzenegger on Wednesday announced he was giving up movies to fight for the governorship of the state of California, in a surprise twist worthy of a Hollywood script.

The Austrian-born "Terminator" star's decision to compete in October elections came in an interview with US talk show host Jay Leno in Los Angeles and stunned fans after weeks of "will he, or won't he" speculation.

"It was a very difficult decision to make, one the most difficult decisions I have made in my entire life," the 56-year-old told Leno of his bid for the leadership of the most populous, and most broke, US state.

"After two weeks, I came to the conclusion that there will be lot of sacrifices to be made," the Republican candidate told reporters after the show.

"Less hours for the children, moving to (the state capital) Sacramento and no movies. But it is my duty to jump into the race and to bring hope to the people in California."