Melt butter in a heavy large Dutch oven over medium-high heat. Add onion, both bell peppers and garlic and saute until peppers are tender, about 15 minutes. Add broth, potatoes, pepper and cumin. Bring to a boil. Reduce heat and simmer until potatoes are tender, about 30 minutes.
Puree half of corn in food processor. Add pureed corn, remaining corn, sausage, 1/3 cup milk and cream to chowder. Simmer until flavors are blended, about 20 minutes. Season chowder to taste with salt and more white pepper, if desired.
Can be prepared 1 day ahead. Cover and refrigerate. Rewarm over medium heat, stirring frequently and thinning with more milk if necessary.
Revised to reduce fat by Linda Shogren, 5/97