Warner Bros. has asked Ben Affleck to direct (and presumably star in) Justice League, according to Variety, but he’s likely to decline, according to Deadline.  Christopher Nolan, who was reportedly asked to oversee all of DC’s movies at Warners (see "Warners Wants Nolan to Shepherd DC Movies"), has now declined; so a less global solution, like Affleck, who proved his chops on The Town, was sought for Justice League. 

But Affleck is unlikely to take on the superteam flick, according to the Deadline report.  Variety points out that Affleck is considering an adaptation of Stephen King’s The Stand, and may also star in the sci-fi film Replay.  Deadline speculates that the tough competition with Avengers creatively and at the box office may also play a role in Affleck’s reluctance to direct Justice League. 

There’s a script for Justice League by Gangster Squad writer Will Beall (see "'Gangster Squad' Scribe Writing 'Justice League' Script"), so the film is ready to move forward once a director is found.