Ghana and Nigeria have pledged their commitment to deepen their political, economic and cultural relations for their mutual benefit.President John Dramani Mahama and the visiting Nigerian Vice-President, Mr Mohammed Namadi Sambo made the commitment Thursday when the latter called on President Mahama at the Castle, Osu in Accra.Vice-President Sambo was at the Castle at the instance of Nigerian President, Goodluck Jonathan, to express condolence on the demise of former President John Evans Atta Mills and to congratulate President Mahama on his elevation to the office of the President.The visit of the Nigerian Vice President followed a letter of notice on the passing on of President Mills that President Mahama sent to his Nigerian counterpart two days ago.President Mahama expressed appreciation at the quick manner in which President Jonathan had sent Vice-President Sambo to Ghana, barely 48 hours after sending him the notice.President Mahama said President Jonathan had already called him to express his condolence.President Mahama eulogized the late President Mills for his performance while in office and said it was difficult to lose him at this stage, but indicated that “God knows best.”President Mahama said the sincerity with which Ghanaians had come together to mourn the late President was a credit to his peaceful, tolerant and humble nature.He said several heads of state had called him to express condolence on the demise of the former President, adding that Ghanaians were encouraged by those calls.President Mahama said the former President had left behind a heavy responsibility for him, and said he would count on the support of President Jonathan and other heads of state to continue with the vision of the late President.He pledged to deepen bilateral relations between Ghana and Nigerian and other ECOWAS member countries.Besides, he said, he would continue with all the regional projects that former President Mills had committed himself to.Earlier, Vice-President Sambo described former President Mills as a statesman and a great African leader who had championed the cause of ECOWAS.He said President Jonathan had asked him to assure Ghana of his support to Ghana in these trying times.