This year marks the 70th birthday of the world's biggest film festival, with A-listers set to grace the glitzy French resort.
This year marks the 70th birthday of the world's biggest film festival, with A-listers including Nicole Kidman, Clint Eastwood and Will Smith set to grace the glitzy French resort amid "unprecedented" tight security.
Miramax supremos Bob and Harvey Weinstein were due to officially announce their backing in Cannes of the new documentary from leftist provocateur Moore, billed as an expose of the US leader.
In "Fahrenheit 11/9" -- a nod to the date Trump was elected, as well as Moore's "Fahrenheit 9/11" that won the Palme d'Or in 2004 and smashed box-office records -- Moore has pledged to take down a president who has so far managed to survive an avalanche of scandals and controversies.
"Facts, reality, brains cannot defeat him. Even when he commits a self-inflicted wound, he gets up the next morning and keeps going and tweeting," Moore said in a statement quoted by Screen International magazine.
"That all ends with this movie."
Italian star Monica Bellucci is set to host Cannes's opening ceremony on Wednesday night, with French drama "Ismael's Ghosts", starring Marion Cotillard, as the opening film.
Spanish director Pedro Almodovar is leading the jury charged with picking a winner amongst the 19 films vying for the coveted Palme d'Or top prize, on a panel that also includes Smith, "Interstellar" star Jessica Chastain, and Chinese actress Fan Bingbing.
Stars are arriving under tighter security than in previous years, 10 months after the truck attack in nearby Nice killed 86 people.
Concrete barriers -- in the form of giant flower pots -- have been set up to try to block a similar assault, and snipers have been positioned above sensitive sites.
Patrick Mairesse, a top regional security official, said the goal was to be as "invisible as possible, to cause as little nuisance as possible -- so the party can stay a party."
Elsewhere at the festival, veteran British actress Vanessa Redgrave is to unveil Wednesday her first film as a director -- "Sea Sorrow", a documentary about Europe's migrant crisis.
This year's programme also points to changes shaking up the film industry, including the march on Hollywood by streaming giants Netflix and Amazon and the arrival of virtual reality.
A row over Netflix, which has hailed Cannes's acceptance of two of its movies as proof of its new status as a major industry player, dominated the run-up to the festival.
The company has refused to screen the two movies in French cinemas because of rules that mean films cannot be streamed from subscription services in France until three years after their traditional box-office release.
A backlash from French cinema chains prompted Cannes organisers to change the festival's rules from next year onwards to insist on a theatrical release -- a move that could effectively ban Netflix from taking part in the future.
Netflix's movie "Okja" about a mysterious giant beast, starring Tilda Swinton and Jake Gyllenhaal, is nonetheless among the most talked-about at Cannes, along with Sofia Coppola's American Civil War thriller "The Beguiled" featuring Kidman and Colin Farrell.
The Australian actress is the undisputed queen of this year's Cannes, starring in three movies as well as the TV series "Top of the Lake", which is getting a special screening.
Others in the running for top honours include "Happy End", another film set against the backdrop of the migrant crisis by "Amour" director Michael Haneke, who is seeking a record-breaking third Palme d'Or.
Another highlight will be Mexican director Alejandro Gonzalez Inarritu showcasing a virtual reality project that allows the viewer to walk in the footsteps of refugees.