President Barack Obama has begun rallying supporters for his 2012 presidential campaign, recognizing that some of the soaring promise of 2008 has been grounded by tough political realities. At two campaign events late Wednesday in California, the first a gathering of wealthy donors at a private residence and the second at a grand hall packed with mostly young supporters, Obama sought to galvanize the troops. \"I understand how you guys feel,\" he said at the second event. \"But we knew this wouldn?t be easy. We knew that on a journey like this there were going to be setbacks. There were going to be detours.\" But he applauded what he views as his greatest successes, including the auto industry rescue, major health care reform, the adoption of new financial regulations and the end of a ban on gays serving openly in the military. At the first event, where donors paid $35,800 each to dine with the president and Stevie Wonder provided the music, Obama took aim at a budget plan advanced by his Republican rivals in the House of Representatives. They have called for cutting back on social programs while preserving tax cuts on top-earners enacted by Obama\'s predecessor, George W Bush. \"That\'s the easy path in some ways. The easiest thing to do is for the rich and powerful to say we\'ve got ours and we don\'t have to worry about the rest. It doesn\'t require a lot of imagination,\" Obama said.\"The easiest way of cutting health care is to stop giving health care to people. But that\'s not the America I believe in. That\'s not the America you believe in. That\'s what 2012 is going to be about. \"We started something in 2008, we haven\'t finished it yet. And I\'m going to need you to finish it.\"At the second event he urged the young supporters who propelled his long 2008 campaign not to lose heart. \"Whenever you hear people say: \'Well the campaign was this or that and now governing is somehow different,? I just want you to think about all the progress we\'ve already made. \"I want you to think about all the unfinished business ahead of us and be excited about the future that lies before us.\" He then closed with his trademark 2008 slogan: \"Yes we can!\" Obama had earlier called on young voters to \"double down\" in 2012 during a campaign-style visit to Facebook headquarters in Palo Alto, California, in which he appeared alongside the company\'s 26-year-old founder Mark Zuckerberg. He was expected in nearby Reno, Nevada on Thursday, where he was to defend his budget plan for a third consecutive day before attending another fund-raising event in Los Angeles.