The early take is that Greece is heading back to the ballot:

“It’s highly unlikely that New Democracy will be able to form a coalition government,” a senior New Democracy party official told Dow Jones Newswires. “There is no common ground with Syriza and there is not enough support in parliament for a coalition with Pasok. Let’s not kid ourselves, we are steaming full speed ahead for new elections in June.”

The popular sentiment seems to be that Greek voters will swing farther to the extremes if they’re forced to vote again. If all parties fail in attempts to form a coalition , a new election could be called as soon as May 16 and take place as soon as June 10.

Update: the 4th place party (Democratic Left) has ended its meeting with Samaras and has no deal.