By Mike Collett-White and Silvia Aloisi

VENICE (Reuters) - Hollywood has turned serious with one eye on the Oscars in February, but it is elsewhere the jury may look when choosing which of 23 competition entries at the Venice film festival wins the Golden Lion on Saturday.

Six U.S. films are in the main lineup, including two movies about the war in Iraq, one about corporate corruption on Wall Street, a retelling of the Jesse James story and a biopic of Bob Dylan in which Cate Blanchett plays the singer and a comedy.

Their inclusion ensured a steady flow of major stars on the red carpet, crucial to the success of any festival.

Brad Pitt was in the canal city with Angelina Jolie and their children, and George Clooney, Woody Allen, Johnny Depp, Charlize Theron and Keira Knightley all wowed the noisy crowds.

Should the jury decide to make a political point, 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, could be in the running, critics said.

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

"I think the film by De Palma is more original and innovative, also because of the use it makes of new media, while the one by Haggis is more of a traditional movie," said Paola Jacobbi, in Venice for the Italian edition of Vanity Fair.

"The only problem with De Palma's film is that it preaches to the converted, it's very ideological."

Jay Weissberg of movie magazine Variety said De Palma "hits you over the head with a sledgehammer.

"You feel you're sitting there being manipulated."

ART OR POLITICS?

If the jury decides to reward pure film making ahead of political cinema, then the pre-award favourite is "The Secret of the Grain" ("La Graine et le Mulet"), directed by Tunisian-born Abdellatif Kechiche.

The movie tells the story of an Arab family in the south of France drawn together by the old father's dream of owning his own restaurant, and is an examination of what the director calls the immigrants' "right to be different".

"The film that everyone's talking about as a possible winner is the Kechiche," Weissberg said. "It beautifully captures a family, a milieu, and you really feel you know these people."

Highly rated by critics, though unlikely to be seen in many cinemas, are arthouse entries "Les Amours d'Astree et Celadon", portraying nymphs and shepherdesses in a rural idyll, and "En la Ciudad de Sylvia" by Spanish director Jose Luis Guerin.

Male leads generally outshone the females, with Casey Affleck in "The Assassination of Jesse James by the Coward Robert Ford" impressing many as a creepy social misfit.

Venice favourite Clooney, who has a home in Italy, was praised for his portrayal of the corporate "fixer" in "Michael Clayton", as was Tony Leung in Ang Lee's "Lust, Caution" and Jones in "In the Valley of Elah."

Among the women, the favourite is British actress Kierston Wareing in Ken Loach's "It's a Free World..." and Blanchett, one of six performers playing Dylan in Todd Haynes' off-the-wall "I'm Not There".

Two Taiwanese competition entries featured graphic sex scenes, and in the case of Lee's espionage thriller, the director hinted heavily that they were real.

Hong Kong film maker Johnnie To's "Mad Detective" was the surprise addition to the main lineup, taking to 23 the number of entries, and the closing movie, which is out of competition, is Chinese action movie "Blood Brothers".