Seven years ago Barack Obama was carried into the White House on a message of hope and change. On Tuesday night, in the final State of the Union speech of his presidency, he sought to recapture that prospect of greatness.With a year left in office, the soaring speech was less a set of policy proposals than the opening gambit in Obama's effort to shape his legacy and help get a Democratic successor into the White House.He used what might well be the biggest prime-time audience he will have as president to call on Americans to believe in the vision he has worked for. He called for Americans not to shy from change and see that during his time in office he sowed the seeds of progress that will bear fruit."We made change work for us, always extending America's promise outward, to the next frontier, to more and more people," he said. "And because we did - because we saw opportunity where others saw only peril - we emerged stronger and better."Aware a Republican president could unravel much of what he worked for, the speech also sought to influence the presidential race.Without naming him, time and again he challenged the views of Donald Trump, the Republican frontrunner who has built much of his campaign by vilifying immigrants and Muslims."We need to reject any politics that target people because of race or religion," said Obama.Obama's approval ratings have languished since the first heady days of his election, with June 2013 the last time he had 50% approval in daily Gallup polls.White House officials are working hard to present Obama as a thoughtful and fearless president who stayed true to his promises.But Obama's legacy as one of America's great presidents is far from set.Loathed by Republicans, he also lacks the backing of his own party, with many Democrats feeling let down by a man they hoped would make reality of their dreams. ..