Uttarakhand Chief Minister Vijay Bahuguna on Wednesday won the Sitarganj Assembly seat by a record margin of 39,954 votes over his nearest BJP rival to retain the top post. The victory margin is the highest in all the Assembly elections in Uttarakhand so far,officials said.Bahuguna defeated BJPs Prakash Pant,a former state minister. Sitarganj byelection was held on July 8 to decide the fate of the Chief Minister,who had to win the election to continue in office. The byelection was necessitated after BJP MLA Kiran Mandal quit in favour of Bahuguna.