Palestinian President Mahmoud Abbas left Washington Tuesday after a three-day visit in which he met US President Barack Obama on helping break the stalemate in US-brokered peace talks with Israel.During their meeting, Obama said: "It's very hard… We're going to have to take some tough political decisions and risks if we're able to move it forward, and I hope that we can continue to see progress in the coming days and weeks."Facing pressure from his own people to hold the line on concessions, Abbas told reporters at the start of the talks, "We don't have any time to waste. Time is not on our side."Abbas thanked the US president on his country's continuous political and economic support to Palestine.Before his meeting with Obama, Abbas had met with US Secretary of State John Kerry to brief him on latest developments.