US President Barack Obama dedicated a national memorial to Martin Luther King, drawing parallels between the civil rights icon\'s struggles and his own push for change at a time of deep economic pain. \"His life, his story, tells us that change can come if you don\'t give up,\" Obama told tens of thousands of predominantly African-Americans gathered on the National Mall in Washington for his highly political 20-minute address. America\'s first black president wasn\'t even in politics when the statue was authorized 15 years ago, and his amazing story would not have been possible without the great strides King\'s generation of activists made for racial equality. Obama paid tribute to the giants of the civil rights movement as well as its foot-soldiers, saying the gleaming granite monument of King looking sternly out over the Tidal Basin to the Jefferson Memorial stood for all. With a bitter 2012 reelection battle looming, the president could not pass up the opportunity of trying to score a few points against his opponents and issued a thinly-veiled assault on perceived Republican obstructionism. \"As was true 50 years ago, as has been true throughout human history, those with power and privilege will often decry any call for change as \'divisive.\' They\'ll say any challenge to the existing arrangements are unwise and destabilizing,\" he said. \"As tough as times may be, I know we will overcome,\" he declared, standing under the imposing monument of the civil rights icon. \"I know there are better days ahead. I know this because of the man towering over us.\" While Obama never explicitly compared himself to King, several parts of the speech could equally have applied to the president. \"It is right for us to celebrate Dr. King\'s marvelous oratory, but it is worth remembering that progress did not come from words alone. Progress was hard,\" he said. \"We forget now, but during his life, Dr. King wasn\'t always considered a unifying figure. Even after rising to prominence, even after winning the Nobel Peace Prize, Dr. King was vilified by many. \"He was even attacked by his own people, by those who felt he was going too fast or those who felt he was going too slow.\"  Obama hailed King\'s \"return to the National Mall,\" for nearby is the Lincoln Memorial from where the pastor gave his famous \"I Have a Dream\" speech on August 28, 1963, helping to galvanize a movement. \"In this place, he will stand for all time, among monuments to those who fathered this nation and those who defended it,\" Obama said. \"A black preacher with no official rank or title who somehow gave voice to our deepest dreams and our most lasting ideals, a man who stirred our conscience and thereby helped make our union more perfect.\" The event had the atmosphere of a political rally as speaker after speaker linked King to today\'s intractable politics, many of them accusing Republicans of stalling Obama\'s jobs agenda for short-term political gain. US civil rights leader Reverend Jesse Jackson, who was a King friend and colleague, attacked such tactics, saying: \"Many seem willing just to sink the ship just to destroy the captain. We must do better than that.\" The icon\'s son, Martin Luther King III, called for an end of \"conservative policies that exclude people\" and praised the Occupy Wall Street movement, saying: \"We must stand up for economic justice.\" Obama also touched on the protests, saying of King that, \"If he were alive today, I believe he would remind us that the unemployed worker can rightly challenge the excesses of Wall Street without demonizing all who work there.\" After the address, the president joined hands with wife Michelle and Vice President Joe Biden to sing the civil rights anthem \"We Shall Overcome,\" swaying with a crowd of thousands in front of the sun-drenched memorial. Hurricane Irene\'s passage through the eastern United States had prompted the postponement of the ceremony on August 28, which was the 48th anniversary of the \"I Have a Dream\" speech. Dedicated to the 1964 Nobel laureate and his message of non-violence and justice, the King Memorial has been installed on a vast open space of four acres (1.5 hectares) dotted with cherry blossom trees that were a gift from Japan nearly 100 years ago. The massive, 28-foot (nearly nine-meter) \"Stone of Hope\" statue in the likeness of King was carved out of white granite by renowned Chinese sculptor Lei Yixin. Visitors enter through the Mountain of Despair, a huge boulder symbolizing the African-American struggle for peace and equality.