The Congress party on Wednesday voiced "deep disappointment" at the resignation of Nitish Kumar as Bihar Chief Minister and said it will try to sort out differences of opinion between partners of the Grand Alliance to see that the five-year assembly victory mandate is respected. "We are deeply disappointed by the news of resignation of Bihar Chief Minister Nitish Kumar. We in the Indian National Congress, particularly, Congress President Sonia Gandhi and Vice President Rahul Gandhi have great respect for Nitish Kumar as a political leader," said Congress spokesperson Randeep Singh Surjewala. "Mahagathbandhan (alliance) was given a five-year mandate by people of Bihar based on its policies, principles and the cumulative leadership that we presented," he added. Surjewala said the 2015 victory "was also a mandate against BJP and leadership of Prime Minister Narendra Modi, who tried to weigh the respect, regard of Biharis in the manner that he chose to do by way of public auction of and distribution of money". "People of Bihar gave respect and regard to Mahagathbandhan based on our policies, principles and leadership," he said. "We shall continue to strive that the mandate given by people of Bihar for a period of five years is fully respected. Any differences of opinion that may have cropped up we will try and sort them out by speaking to each other in an amicable and cordial fashion." Earlier, Nitish Kumar quit on Wednesday as Chief Minister claiming he can't work in the "current circumstances" following corruption allegations against Deputy Chief Minister Tejashwi Yadav but didn't rule out a tie-up with the BJP for running a future government.