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, one third 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, 0.051546391752577