Stir the soup, cour cream, picante sauce and chili powder in a medium bowl.
Stir 1 cup soup micture, chicken and cheese in a large bowl.
Divide the chicken mixture among the tortillas. Roll up the tortilas and place them seamside up in a 11 x 8" shallow baking dish. Pour the remaining soup mixture over the filled tortilas. Cover the baking dish.
Bake at 350 degrees for 40 min., or until the enchiladas are hot and bubbling. Top with the tomato and onion.