Beck insists the event Saturday at the Lincoln Memorial is not about politics, even though Beck and former Alaska Gov. Sarah Palin, a potential 2012 presidential candidate, will attend. But the rally is drawing a strong reaction - and several counter-rallies - as the nation looks toward November's elections.
Beck, a popular figure among tea party activists and a polarizing Fox News Channel personality, has said it is merely a coincidence that the event is taking place on the 47th anniversary of King's plea for racial equality. Beck has called President Barack Obama a racist.
The event's website says the "Restoring Honor" rally is to pay tribute to America's military personnel and others "who embody our nation's founding principles of integrity, truth and honor." It urges citizens to attend and "help us restore the values that founded this great nation."
"This is going to be an iconic event," Beck says. "This is going to be a moment that you'll never be able to paint people as haters, racists, none of it. This is a moment, quite honestly, that I think we reclaim the civil rights movement. It has been so distorted and so turned upside down. It is an abomination."
The rally also is to promote the Special Operations Warrior Foundation, which provides scholarships and services to family members of military members.
Beck's critics dismissed his claims that the event will not be political.
"When we heard about Glenn Beck, it was puzzling," the Rev. Al Sharpton said. "Because if you read Dr. King's speech, it just doesn't gel with what Mr. Beck or Mrs. Palin are representing."
Beck has called Obama "a guy who has a deep-seated hatred for white people or the white culture."
"I'm not saying he doesn't like white people. I'm saying he has a problem," Beck said. "This guy is, I believe, a racist."
Palin has defended radio personality Laura Schlessinger, who announced this month she was ending her "Dr. Laura" program after using a racial epithet repeatedly on the air during a discussion with a caller about racism. Schlessinger later apologized but said her free speech rights were being violated by those urging station affiliates and sponsors to drop her program.
"Dr.Laura:don't retreat...reload!" Palin tweeted. She called Dr. Laura "even more powerful & effective w/out the shackles, so watch out Constitutional obstructionists. And b thankful 4 her voice,America!"
"The 8-28 rally is supposedly is about 'reclaiming the civil rights movement,' but it is being led by someone whose idea of a racist is the president of the United States," said Jess Levin, a spokesman for the liberal Media Matters for America, an organization that has targeted Beck, Fox News Channel and Schlessinger. "This rally is about one thing and one thing only. And that's promoting Beck's political agenda."
Elsewhere in Washington, civil rights activists planned to mark Saturday's anniversary of the landmark 1963 speech with rallies and demonstrations, some ending on the National Mall. One group planned a four-story sculpture in honor of King near the Washington Monument. Others planned to meet at a Washington school.
Sharpton's National Action Network plans a "Reclaim the Dream" rally that will feature Education Secretary Arne Duncan, National Urban League president Marc Morial and Martin Luther King III.
In an opinion piece for The Washington Post, King said of Beck's event that it's "commendable that this rally will honor the brave men and women of our armed forces who serve our country with phenomenal dedication." But he also said it was clear the organizers were invoking his father's work.
"My father championed free speech. He would be the first to say that those participating in Beck's rally have the right to express their views," King wrote Wednesday. "But his dream rejected hateful rhetoric and all forms of bigotry or discrimination, whether directed at race, faith, nationality, sexual orientation or political beliefs."
Organizers of Saturday's rally advise attendees not to bring signs, "as they may deter from the peaceful message we are bringing to Washington."
Signs at some tea party events have included pictures of Obama embellished with a Hitler-style mustache, racial epithets and threats to Democratic officials. They gave tea party critics grounds to claim the loose organization of activists was motivated by racism against the nation's first black president.
"Dr. King never had to ask anyone to leave their signs and guns at home," said Benjamin Todd Jealous, president of the NAACP. "To say to your followers, don't bring your signs - it's like saying don't open your mouth."
In the 47 years since King's speech, it has become a staple of civil rights history.
"I have a dream that my four little children will one day live in a nation where they will not be judged by the color of their skin but by the content of their character," he said on Aug. 28, 1963.
On Wednesday, Beck again sought to play down comparisons to the slain civil rights leader.
"I know that people are going to hammer because they're going to say, 'It's no Martin Luther King speech,"' Beck told his radio listeners on Wednesday. "Of course it's not Martin Luther King. You think I'm Martin Luther King?"
Civil rights leaders, too, hoped Beck wouldn't exploit the King legacy at the spot. But the imagery - a packed lawn listening to a speaker standing in the shadow of Lincoln - was certain to draw comparisons.
"I hope that's not what he's trying to do. I hope that this is a coincidence," Jealous said. "But more than anything, I hope that he, having chosen this day and this locations, pushes himself to really honor the unifying legacy of Dr. King.