President Barack Obama on Thursday threw his weight behind the tumultuous drive for democratic change in the Arab world and presented his most detailed vision yet on the path to elusive Israeli-Palestinian peace.

Obama, in his much-anticipated “Arab spring” speech, hailed popular unrest sweeping the Middle East as a “historic opportunity” and said promoting reform was his administration’s top priority for a region caught up in unprecedented upheaval.

He also ratcheted up pressure on Syrian leader Bashar al-Assad, saying for the first time that he must stop a brutal crackdown or “get out of the way,” and prodded U.S. allies Yemen and Bahrain as well for democratic transformation.

Obama’s bid to reset ties with a skeptical Arab world was aimed at countering criticism over an uneven response to the region’s uprisings that threaten both U.S. friends and foes and his failure to advance Israeli-Palestinian peacemaking.

His blunt language toward U.S. ally Israel about the need to find an end to its occupation of Arab land could complicate his talks on Friday with Israeli Prime Minister Benjamin Netanyahu while easing Arab doubts of his commitment to evenhanded U.S. mediation.