By Mike Collett-White

VENICE, Sept 8 (Reuters) - The guessing game is almost over at the Venice film festival, where few clear frontrunners for the Golden Lion award for best picture have emerged ahead of the prize ceremony on Saturday evening.

By the end of the annual 11-day marathon of movies, press conferences, interviews and parties, critics and journalists normally agree on a handful of films they think could win the top honour, although their predictions are not always correct.

Last year, for example, Stephen Frears' "The Queen" was favourite to take the Golden Lion, but it went instead to a late entry from China which many had not even seen.

This year the favourite by a slight margin is "The Secret of the Grain" ("La Graine et le Mulet") by Tunisian-born Abdellatif Kechiche, although much depends on whether the jury favours political cinema over arthouse film, or seeks a combination of the two.

"No film has really stood out in people's minds as saying this is absolutely a winner, but I think that makes it more exciting, it means that people are guessing to the very last minute," said Jay Weissberg of Hollywood trade paper Variety.

Of the six U.S. productions in competition, two were about the Iraq war and one was on corporate corruption. There was also an Egyptian movie about police brutality, an Italian entry on the mafia and a British film about migrant labour.

At the other end of the spectrum, "En la Ciudad de Sylvia" by Spain's Jose Luis Guerin features virtually no dialogue and "Les Amours d'Astree et de Celadon" by France's Eric Rohmer is about nymphs and shepherdesses in a rural idyll.

Kechiche's film is not overtly political, but his tale of an Arab family seeking to realise a dream in southern France does touch on problems of integration by immigrants and whether they have what the director calls the "right to be different".

STAR POWER

Festival director Marco Mueller, facing competition from festivals in Rome and Toronto, succeeded in attracting some of Hollywood's biggest stars, although his decision to invite so many U.S. films was criticised for making Venice too commercial.

Brad Pitt and Angelina Jolie came to the canal city with their children, and George Clooney, Woody Allen, Johnny Depp, Charlize Theron and Keira Knightley all wowed the noisy crowds gathering along the red carpet each night.

One of the most talked-about films in competition was Brian De Palma's shocking "Redacted", which reconstructs the real-life rape of a 14-year-old Iraqi girl and her murder by U.S. forces.

It divided critics, however, between those who favoured the direct approach to portraying the war in Iraq and those who felt it was heavy-handed and sloppy film making.

Paul Haggis' "In the Valley of Elah" about a soldier murdered after returning from Iraq, was more subtle and universally popular, particularly because of the strength of Tommy Lee Jones' lead performance.

Several male stars caught critics' attention this year, notably Casey Affleck in "The Assassination of Jesse James by the Coward Robert Ford", Clooney as the corporate "fixer" in "Michael Clayton" and Tony Leung in Ang Lee's "Lust, Caution".

Among the women, the favourite to win was British actress Kierston Wareing in Ken Loach's "It's a Free World..." and Cate Blanchett, one of six performers in off-the-wall casting to play the singer Bob Dylan in Todd Haynes' off-the-wall biopic "I'm Not there".

(For blogs about the Venice film festival, please see:

http://blogs.reuters.com/category/events/venice-2007/)