 यथावयो हि राज्यानि प्राप्नुवन्ति नृपक्षये। इक्ष्वाकुकुलनाथेऽस्मिं स्तल्लोपयितुमिच्छसि।। 
 After the death of the king, the princes will obtain the kingdom according to   seniority. Why do you want to break this tradition in the case of Rama, the lord of the Ikshvaku dynasty?  