President Mikhail S. Gorbachev has postponed a trip to Oslo next month to receive the Nobel Peace Prize because of domestic political and economic problems, Tass reported today. The official Soviet news agency said Gorbachev hoped the Nobel Committee would agree to postpone the Dec. 9-10 ceremonies and present him the prize at a later unspecified date. Gorbachev postponed the trip ``due to the crucial situation in the country and the president's preoccupation with affairs that require his constant attention,'' his press office said. In Oslo, Nobel Committee secretary Geir Lundestad would not comment on the Soviet request. Gobbachev is struggling to hold his geographically and ethnically diverse country together in the face of mounting nationalism and independence drives by the 15 republics. The Soviet Union also faces a grave economic crisis.