If a deal isn’t struck by the end of May, it is truly game over. Here’s the ECB’s Yves Mersch:

“We are in an end game in Greece where the situation is grave. This situation is not tenable. There has been an accord between Europe and Greece to go through a program. This hasn’t been the case since December last year, because the new government said it doesn’t want to have anything to do with the program. But then they can’t demand money that was attached to that program either. In the meantime, they haven’t managed to bring other measures to the table that could lead to the same goal as foreseen in the first program. Greece is convinced it can play along the line of other rules than” the other 18 euro-area members.”

http://www.zerohedge.com/news/2015-05-16/greece-will-default-june-5-without-deal-imf-leaks