ATHENS — Despite pressure from lenders for Greece to show a unified front in solving its debt crisis, Prime Minister George A. Papandreou had little apparent success Tuesday in persuading his political rivals to back additional tax increases and spending cuts.

In Brussels, meanwhile, frustration at the slow pace of privatization efforts in Greece has given new momentum to calls within the European Union for an external agency to manage sales of state assets, an idea floated last week at a meeting of E.U. finance ministers.

The Socialist government in Athens has sought to respond to charges of foot-dragging by Greece’s European partners by announcing new initiatives to raise revenue, in order to secure the next installment of emergency financing from the European Union and International Monetary Fund.

Late Monday, the government said it would proceed “immediately” with the sale of stakes in the telecommunications operator O.T.E., the country’s main ports of Piraeus and Thessaloniki and the state-owned Hellenic Postbank. The Finance Ministry would not say how much it aimed to raise. Other assets, including the country’s biggest electricity producer, P.P.C., and the horse-racing company O.D.I.E., are on a list of assets that Greece plans to privatize, in whole or in part, by 2015.