At the end of last week, there was a Haaretz article that spoke of Kerry working with Assad on this. Haartez is a mayor, left leaning Israeli paper, that is often the one named when people ask for a good source of Israel/Palestinian news.
Here is Friday's article. I didn't post it when I saw it then because Kerry's spokesperson seemed to deny when he was quoted at the end of the article. The ideas seemed consistent with things that were said in wikileaks and it seemed the story might to some degree have been based on that. (Netabyahu was said to be against it.)
http://www.haaretz.com/print-edition/news/u-s-lawmaker-syria-s-assad-working-to-renew-peace-talks-with-israel-1.345303Today, this has more wide spread coverage and the Ehud Barak, the defense minister, is open to the idea. "Defense minister says that if Syrian president will reach out to Israel, he will find a willing partner, also says Israel must strengthen peace efforts with Palestinians."
http://www.haaretz.com/news/diplomacy-defense/barak-assad-ready-to-consider-israel-syria-peace-deal-1.346212No one has worked harder to develop a dialog with Assad than Kerry - and it is impossible to see how a comprehensive settlement of the Mideast could happen without Syria. In the Wikileaks documents, Kerry push backed against the ruler in Doha saying that Assad had not yet done anything to gain trust - and he mentioned Iran and Hezzbollah. I can't imagine how that would have changed for the better with Hezzbollah controlling the Lebanese government, but these articles are interesting.
Whether Kerry has worked on a proposal with Assad or not, if Assad is moving toward an agreement with Israel, Kerry might have had a role over the last several years in pulling Assad away from Iran and terrorism.
( If you look at the last week the Senate was in session - Kerry did not vote all week. He departed Pakistan on Feb 16 (
http://www.uspolicy.be/headline/state-department-daily-press-briefing-february-16 ) He was back in MA on February 18, where he was filmed at the airport. That really leaves little time to have stopped anywhere in between.)