"I want to say a heartfelt thanks to the majority of Greeks who stood by the Greek government ... That was our most powerful negotiating weapon," he said on Saturday. "Greece achieved an important negotiating success in Europe.".
Top Marxist members of Tsipras's Syriza party, a broad coalition of the left, have so far been silent on the painful compromises made to win agreement from the Eurogroup.
But veteran leftist Manolis Glezos attacked the failure to fulfil campaign promises. "I apologize to the Greek people because I took part in this illusion," he wrote in a blog. "Syriza's friends and supporters ... should decide if they accept this situation."
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Glezos, a Syriza member of the European Parliament, is not a party heavyweight. But he commands moral authority: as a young man under the World War Two occupation, he scaled the Acropolis to rip down a Nazi flag under the noses of German guards and hoist the Greek flag, making him a national hero.
A government official said Glezos "may not be well informed on the tough and laborious negotiation which is continuing".
Finance Minister Yanis Varoufakis said the reform promises would be ready on Sunday and submitted to Greece's EU and IMF partners in good time. "We are very confident that the list is going to be approved by the institutions and therefore we are embarking upon a new phase of stabilisation and growth," he told reporters late on Saturday.
A government official said the reforms would include a crackdown on tax evasion and corruption.
The Brussels deal opens the possibility of lowering a target for the Greek primary budget surplus, which excludes debt repayments, freeing up some funds to help ease the effects of 25 percent unemployment and pension cuts. It also avoids some language which has inflamed many Greeks, angered by four years of austerity demanded by foreign creditors.
Troika no more?
In the deal the hated "troika" of inspectors from the European Commission, European Central Bank and IMF, which monitors compliance with Greek bailout undertakings, is referred to as "the three institutions".