Marathon talks toward a historic nuclear deal between Iran and major powers went late into the night July 6, with both sides saying more time might be needed.
The White House said another "slip" beyond the target date of July 7 was "certainly possible." An Iranian official at the negotiations in Vienna said: "Even if we pass July 9, that will not be the end of the world."
Negotiators have missed deadlines before in their almost two years of seesaw talks. They in fact have typically come to agreement after self-imposed deadlines.
In April, several days late, they announced a framework accord. The current target date was pushed back from June 30.
By the evening of July 6, it became clear there was still no light at the end of the tunnel, despite some progress clinching final details of an accord.
"We are not there yet... We should not underestimate that important questions remain unresolved. There will not be an agreement at any price," a German source said. "If there is no movement in decisive areas, a failure is not ruled out."
Based on reporting by AFP and RFE/RL's Radio Farda