Mushroom-Cheese Fondue

1 (10 1/2 ounce) can condensed cream of mushroom soup
2 cups shredded cheese
1/2 cup sour cream
2 tablespoons prepared mustard
1 teaspoon Worcestershire sauce
1/8 cup finely chopped chives

In saucepan, heat soup over low heat; add cheese, sour cream, mustard and Worcestershire sauce. Stir until cheese is melted.