Iron Man vs Captain America: Iron Man to Play Big Role in 'Captain America 3'?

The sequel to "Captain America: The Winter Soldier" will reportedly feature another Marvel Superhero, Iron Man, who is expected to play a key role in the movie.

According to Variety, Robert Downey Jr. (who plays Iron Man) is being talked to sign for "Captain America 3." The film's storyline will reportedly follow the events taking place amid a civil war. The production team will begin filming early 2016, according to the online news source.

The plot will allegedly have Tony Stark (aka Iron Man) battling against Steve Rogers (aka Captain America, played by Chris Evans).

Stark supports a plan to have all the superheroes reveal themselves to the U.S. government and register in a program to become part of the country's police force. Rogers, however, rejects the program, saying it threatens "civil liberties. Stark then becomes a villain of sorts.

Marvel has announced that it plans to do another batch of Civil War comic books to introduce new characters to the readers, leading up to the plot for "Captain America 3."

According to Variety, the original plan was to hire Downey to play a small role in the film. But the actor reportedly wanted a longer screen time and thus bigger pay for what was initially just a cameo role.

Variety reported that this angered the Marvel Productions and asked for Downey to be taken out of the script entirely.

However, other reports say that Downey's role is still being negotiated with Marvel.

Variety reports that "Marvel has long been known as a tough negotiator — and by some accounts cheap — but the studio hasn't shied away from giving Downey what he's asked for in the past."

Downey has so far reaped between $250 million and $300 million for the "Iron Man" trilogy, his role in "The Avengers" films and a brief appearance in "The Incredible Hulk," according to knowledgeable sources.