Congress MP Adhir Ranjan Chowdhury has apologised to President Droupadi Murmu for calling her "Rashtrapatni" in a media interview earlier this week. "I am writing to express my regret for having mistakenly used an incorrect word to describe the position you hold. I assure you that it was a slip of the tongue. I apologise and request you to accept the same," Mr Chowdhury wrote in a letter to President Murmu, the country's first President from the tribal community.