Prime Minister Alexis Tsipras faced anger and resistance on Tuesday from members of his own radical left political party, complicating his efforts to strike a deal this week with Greece ’s creditors, as some lawmakers and party officials criticized concessions by the Greek side and expressed doubts about voting for a deal in Parliament. Mr. Tsipras returned to Athens on Tuesday afternoon after negotiations in Brussels brought predictions that a deal would be completed by the end of the week, in which creditors would unlock bailout funding so that Greece can stave off default in exchange for concessions on tax increases and pension changes. Less clear, if critical in the eyes of Greek leaders, is a potential European promise for future debt relief. […]