Combine tomato sauce, pinto beans, black beans, corn, onion, bell pepper, garlic, jalapeno, tomatoes, chili powder, cumin, oregano, and pepper in a 6 quart slow cooker. Place chicken breasts on top and cover with the lid.
Cook on high for 4-6 hours or low for 8-10 hours. Before serving, remove chicken and shred using two forks. Return to chili and stir well. Serve topped with your favorite chili toppings.