A striking contrast between the 1963 March on Washington and Wednesday's 50th anniversary celebration of it (and of Martin Luther King's historic "I have a dream" speech) was the visible unity and nonpartisanship of the first and the scarcity of both in the second.

In the voices the other day of three Democratic presidents -- Jimmy Carter, Bill Clinton and Barack Obama -- and of not a single prominent Republican leader, past or present, the program seemed at times more a self-congratulatory Democratic rally.

The remarks of Presidents Carter and Clinton necessarily reflected on the progress toward racial justice and equality during their administrations. President Obama's oration, no match for King's inspirational call for perseverance, left the Republican Party largely on the outside looking in at the event at the Lincoln Memorial.

The granite presence of the Great Emancipator peering down on the speakers was a solitary and silent reminder that the quest for racial justice and equality was at its most significant core a Republican initiative. Eventually it was advanced by a liberal Democratic Party that embraced the crusade in the great civil rights battles of the 1960s.

The two living former Republican presidents, the senior and junior George Bushes, did not attend, on legitimate grounds of health circumstances. But no such complications kept Republican congressional leaders away, their aides explaining scheduling or other barriers. Many other prominent GOP figures past and present could have filled the conspicuous absence at the microphone.

President Obama, while paying lip service to the nonpartisan unity that marked the March on Washington of half a century earlier, artfully underscored the partisan flavor of the anniversary event. He made repeated observations on the disunity that now grips the nation's capital and a politically divided Congress.

Seizing on one King line, Mr. Obama noted that while "the arc of the moral universe may bend towards justice, it doesn't bend on its own." It "requires constant vigilance, not complacency," he said, "whether it's by challenging those who erect new barriers to the vote" or other injustices.

The comment took dead aim at the conservative Republican majority on the Supreme Court that had recently weakened a critical section of civil rights legislation earlier overwhelmingly supported on a bipartisan basis by a functioning Congress.

The president went on to recite the core of the Democratic arguments against today's Republican economic theory. He cast that theory, with income inequality at its root, as a war on the American middle class, of which he has declared himself and his party the prime defenders.

"Even as corporate profits soar," he lectured, "even as the pay of a fortunate few explodes, inequality has steadily risen over the decades. ... The test ... never has been whether the doors of opportunity are cracked a bit wider for a few. It was whether our economic system provides a fair shot for the many. ... This remains our great unfinished business."

With new technology and global competition eroding job opportunities, Mr. Obama said, "entrenched interests, those who benefit from an unjust status quo, resisted any government efforts to give working families a fair deal, marshalling an army of lobbyists and opinion makers" to argue "against stronger labor laws or taxes on the wealthy" required to meet the urgent needs of the broader society. He said these interests argued "that greed was good and compassion ineffective, and those without jobs or health care had only themselves to blame."

Mr. Obama pointedly took on "those elected officials who found it useful to practice the politics of division, doing their best to convince middle-class Americans of a great untruth, that government was somehow itself to blame for their growing economic insecurity -- that distant bureaucrats were taking their hard-earned dollars to benefit the welfare cheat or the illegal immigrant."

Since King's speech of 50 years ago, Mr. Obama asserted, his "transformative message of unity and brotherhood was drowned out by the language of recrimination" against beneficiaries of government social welfare programs, which remain at the heart of the political discourse in today's Washington.

Perhaps it was understandable that all those Republican leaders stayed away from the anniversary march, which in Mr. Obama's remarks became as much another campaign speech as a tribute King and the marchers of half a century ago.

Jules Witcover is a former longtime writer for the Baltimore Sun. His latest book is "Joe Biden: A Life of Trial and Redemption" (William Morrow). You can respond to this column at juleswitcover@comcast.net.