Prime Minister Alexis Tsipras returned to face a mutiny within his coalition after he surrendered to European demands for action to qualify for up to 86 billion euros (US$95 billion) of aid Greece needs to stay in the euro.

Tsipras arrived back in Athens to confront lawmakers from his Syriza-led bloc who rebelled this weekend when he sought their endorsement for spending cuts, pensions savings, and tax increases. He met with his closest aides to chart the path ahead, as the Greek parliament faced a Wednesday deadline to pass into law key creditor demands including a value-added tax overhaul, broadening the tax base to increase revenue and curbing pension costs.

With the threat of defections rippling through his bloc, Tsipras will "have to change his administration and clear out hard-liners and radicals from his party," as well as rely on opposition support to pass the necessary measures, said Eurasia Group analysts Mujtaba Rahman and Federico Santi. "But it is a tough call to determine how Tsipras will go about doing this."