Politics loomed over the ceremonies held Monday to mark the Rev. Martin Luther King Jr.'s holiday as black clergy, elected officials and others tied the civil rights icon's legacy to the 2012 election, urging African-Americans to re-elect President Barack Obama and condemning voter ID laws they warned are meant to suppress black voters.

Monday was the federal holiday marking King's birthday. He would have turned 83 on Sunday.

In Atlanta, at Ebenezer Baptist Church — where King preached from 1960 until his death in 1968 — the Rev. Raphael G. Warnock accused GOP presidential candidate Newt Gingrich of using racial stereotypes to fire up Republican voters. On the campaign trail, Gingrich has referred to Obama as "the food stamp president" and earlier this month, he suggested that African-Americans seek paychecks rather than public assistance.

Warnock called Gingrich's comments "sickening and insulting."

The pastor also said some in America disrespect King's legacy by "cutting off those for whom he died and the principles for which he fought," pointing to voter ID laws that he called "unnecessary and unjustifiable." He said such laws are an affront to the memory of the civil rights leader, who fought for equal access to the voting booth.

"You cannot celebrate Dr. King on Monday, and undermine people's ability to vote on Super Tuesday," Warnock said. He told the audience, "With your voice and your vote, let freedom ring!"

"Mr. Gingrich, we know what work ethic is," Warnock said. "We arrived on these shores on a jobs program. You're a historian, you remember."

Monday's ceremony was the 44th annual commemorative service honoring King. The service was presided over by his only living sibling, Christine King Farris.

King's youngest daughter, the Rev. Bernice A. King — who was recently named chief executive officer of The King Center — also attended Monday's service in Atlanta. She challenged any businesses holding sales on the holiday weekend celebrating her father's birthday to send 10 percent of their profits to The King Center, reminding them that Monday is "a day on, not a day off."

Congressman David Scott recalled blacks and whites during the civil rights movement who gave their lives so that later generations would have the right to vote, and urged the crowd to remember their sacrifice.

"They'd say in one loud voice, go vote in 2012! Vote like you never voted before! And they'd say there's only one person to vote for, and his name is President Barack Obama! Run and don't get weary . all the way to the polls."

Atlanta Mayor Kasim Reed, an Obama surrogate, also tied the president's re-election campaign to an extension of the civil rights movement. He said it was time to get to work and dream again.

"The people that have made it possible have never asked us for anything," Reed said. "All they've asked us to do is to be worthy of their sacrifice."

The Rev. Cameron Alexander, the longtime pastor of former GOP presidential hopeful Herman Cain, said that any black people in Atlanta who don't register to vote "ought to be tarred and feathered."

Alexander, a follower of King and pastor of Antioch Baptist Church North, stopped short of urging the largely black crowd at Ebenezer Baptist Church to vote for Obama. Instead, Alexander, who grew up in the Jim Crow South, recalled the indignities of segregation and remembered King as a preacher, not a politician.

"There ought to be a hurting and an aching to the point that you do something, and that's vote," Alexander told the audience.

Gov. Nathan Deal urged fellow Georgians to be mindful of the challenges that remain more than 40 years after King's death, including illiteracy, addiction, poverty and crime.

"Dr. King was not just a man of words . he was a man of action," Deal said. "So today, when many of the overarching causes for which he worked have been achieved, the question that comes to our generation is, what now?"

U.S. Senator Johnny Isakson took the occasion to endorse the Interior Department's recent decision to change a quote on the Martin Luther King Jr. national monument in Washington after concerns were raised that the civil rights icon's comments were taken out of context and depicted him as arrogant.

"He walked humbly with his God, and he urged others to do the same," Isakson said of King. "Words matter. Dr. King mattered."

The keynote speaker, the Rev. Frederick D. Haynes III, delivered a fiery sermon incorporating the holiday's motto to "remember, celebrate and act."

"Racism is so sinister, subtle and subliminal . we still have a mission to fulfill," said Haynes, the senior pastor of Friendship-West Baptist Church in Dallas. "Even though there are those who have done well . there are countless individuals being left behind, and we cannot forget them."

Haynes said that with so many using King's words but not following his message, the 1964 Nobel Peace Prize winner could be "a victim of identity theft." He reminded the audience that King was not only a dreamer, but one who fought for changes in public policy and sacrificed for the greater good.

"If we're going to make a difference in this world, we need somebody to get agitated," Haynes said. "You don't get killed for dreaming."