Yes there is offline co-op. Start the single-player campaign up as you would usually, once you take control of the character (after loading is finished) have second player press start on another controller. Doing this will enable co-op gameplay and needs to be done everytime you want to play Split-screen. There is also offline system-link available which requires two consoles with two copies of the game.
**Note that these instructions are also in the game manual.