European institutions voiced “serious concerns” about Greece's ability to repay its debt as Prime Minister Alexis Tsipras prepared for a renewed showdown with party rebels in parliament to try to pass a third bailout.

Greece's obligations will peak at 201 percent of gross domestic product next year, before dropping to 160 percent in 2022 under a new rescue program, according to European institution projections in a document obtained by Bloomberg. That exceeds the 120 percent level sought in the past by the International Monetary Fund (IMF) before putting its own money on the line.

Greek lawmakers are expected to vote on legislation by Friday morning that's required to unlock as much as 86 billion euros (US$96 billion) of aid before a 3.2 billion-euro payment comes due to the European Central Bank (ECB) on Aug. 20. The parliamentary action is necessary to assuage Greece's lenders and would pave the way for euro-area finance ministers, who meet in Brussels on Friday, to come to a political agreement on the rescue package.