A senior ally of Chancellor Angela Merkel insisted that there is no room for concessions to Greece on fulfilling the conditions of its aid program and said in an interview published Sunday that he sees little chance of Germany's governing coalition supporting a third rescue package.

Greek Prime Minister Antonis Samaras is to visit Germany and France over the next week as Europe awaits a report next month from debt inspectors on Greece's progress in implementing reforms and austerity measures demanded in exchange for two massive bailout packages.

Signs of slippage on those measures have fueled impatience with Athens in Germany and other prosperous nations and speculation about a possible Greek exit from the 17-nation euro. There's little enthusiasm among creditor countries for granting Greece more time or other concessions.

"The Greeks must stick to what they agreed to," Volker Kauder, the parliamentary leader of Merkel's conservative bloc, was quoted as telling the weekly Der Spiegel. "There is no more latitude, either on the timeframe or the matter itself — because that would again be a breach of agreements. It is just that which led to this crisis."

Asked whether he could imagine a third rescue package for Greece, Kauder replied that officials will have to wait for the international debt inspectors' report — "but I see little chance in the (governing) coalition for a third aid package."

Nearly all eurozone rescue decisions need the endorsement of Germany's Parliament. Bailing out strugglers hasn't been popular in Germany, and the prospect of endless rescues is particularly unpopular in the ranks of Merkel's center-right coalition.

Kauder said that a Greek bankruptcy would be expensive for Germany "but agreements must be kept to."

"There cannot always be new programs or watered-down conditions," he was quoted as saying. "The Greeks must at some point answer the question: do we perhaps make even more of an effort, or do we leave the euro?"

German Cabinet members also have shown little appetite for further concessions. Finance Minister Wolfgang Schaeuble said on Saturday: "I have always said that we can help the Greeks, but we cannot responsibly throw money into a bottomless pit."