Credit: AP Photo

By MICHAEL FALCONE ( @michaelpfalcone )

NOTABLES

• 'LET FREEDOM RING': Tens of thousands of people are expected to descend on Washington, DC's National Mall today to commemorate the 50th anniversary of the Rev. Martin Luther King Jr.'s "I Have a Dream" speech and the March on Washington that took place half-a-century ago. President Obama will address the crowd this afternoon from the Lincoln Memorial as well as two of his predecessors, former presidents Bill Clinton and Jimmy Carter. The event, hosted by television personalities Soledad O'Brien and Hill Harper, will also feature members of the King family, lawmakers and civil rights leaders including Rep. John Lewis, D-Ga., who spoke at the 1963 march and will do so again today. There will be more than few celebrity appearances too. Look for Oprah Winfrey and actors Jamie Foxx and Forest Whitaker and musical performances by BeBe Winans, LeAnn Rimes and Natalie Grant. NOTED: The event, which kicks off at 11 a.m. ET, is being organized by The King Center and The Coalition for Jobs, Justice and Freedom. WATCH ABC's BYRON PITTS "Good Morning America" interview with John Lewis: http://abcn.ws/1aPqpIe

• THE STAKES FOR OBAMA: "For a president who could use a fresh start - not to mention a break from world events - this is an anniversary that matters," ABC's RICK KLEIN notes. "President Obama has always been cognizant of his place in history. Coincidence - accepting the Democratic presidential nomination on the mountaintop of Denver, on the 45th anniversary of 'I have a dream' - has been in his friend. The 50th anniversary of the March on Washington is a bookend not just for Martin Luther King Jr.'s dream but for President Obama's hope. It's also a chance for the president to reach back into history to find a message for the remaining years of his presidency. His challenges are broader, of course, than those voiced by King; the split-screen moment with Syria demonstrates that. But the president's challenge, in playing Joshua in front of a crowd that knew and knows Moses still, is to remind the nation of the broader stakes his presidency represented at its start."

• WHEN THE CLOCK STRIKES THREE: "Organizers said sites in nearly every state will ring their bells at 3 p.m. their time Wednesday or at 3 p.m. EDT, the hour when King delivered his 'I Have a Dream' speech in Washington," according to the Associated Press. "Commemorations are planned from the site of the speech in Washington to the far reaches of Alaska, where participants plan to ring cow bells along with church bells in Juneau. On Aug. 28, 1963, as King was wrapping up his speech at the Lincoln Memorial, he quoted from the patriotic song, 'My Country 'tis of Thee.' King implored his audience to 'let freedom ring' from the hilltops and mountains of every state in the nation, some of which he cited by name in his speech. … International commemorations will be held at London's Trafalgar Square, as well as in the nations of Japan, Switzerland, Nepal and Liberia." RE-READ KING's ICONIC SPEECH: http://abcn.ws/pMeqio

• #IMARCHFOR: Today, as we commemorate the 50th anniversary of the March on Washington, we're reminded once again of the power of a peaceful protest, and the ability of Americans to come together to enact change. ABC News wants to know: What are the causes that you care most about? What issue would get you marching? Share with us on Twitter using the hashtag #IMarchFor or tell us here: http://abcn.ws/1dcgJJD

TUNE IN: ABC News and Yahoo! News will host a first-ever live global broadcast today to commemorate the 50th anniversary the March on Washington. This hybrid digital-television event will be anchored by GEORGE STEPHANOPOULOS along with DAN KLOEFFLER from ABC News World Headquarters in New York beginning at 11:00 a.m., ET. When President Obama speaks from the steps of the Lincoln Memorial, ABC News will simulcast a live special report to the ABC Television Network and to the Yahoo!-ABC News Network. http://abcn.ws/16OtUdG

THE TEAM: ABC News will have a team of correspondents, anchors, and guests contributing to its anniversary coverage throughout the day: COKIE ROBERTS and renowned Harvard Law Professor Charles Ogletree will provide insights and historical context from ABC News Headquarters in New York. Ogletree is the founder of Harvard's Charles Hamilton Houston Institute for Race and Justice. Chief National Correspondent and Anchor BYRON PITTS will lead the network's coverage from the Lincoln Memorial. LINSEY DAVIS will join him there. Senior Justice Correspondent PIERRE THOMAS will report from Washington. Senior National Correspondent JIM AVILA will report from the White House. ABC News Radio Correspondent VIC RATNER, who covered the March on Washington in 1963, will tell viewers what it was like to report on the historical event 50 years ago.

MARCH ON WASHINGTON - 50 YEARS LATER

VOTING RIGHTS FIX TESTS CIVIL RIGHTS MOVEMENT'S STRENGTH. The same Voting Rights Act that grew partially from the March on Washington 50 years ago into one of the most successful civil rights-era laws has become a source of rancor, even straining the traditional coalition of Republicans and Democrats who have come together in favor of such vigilance, ABC's ABBY PHILLIP writes. Marking half a century since the Rev. Martin Luther King Jr. King gave voice to the aspirations of millions of African-Americans across the country is bittersweet for civil rights activists in 2013. "Within the civil rights movement, there is definitely a sense that there's a continued war on voting and we haven't made it to the mountain top yet," said Katherine Culliton-González, director of Voter Protection for the Advancement project. "Here we are in 2013, at the 50th anniversary of the March on Washington, and we're having to try to stop going backwards." Blacks have never been closer than now to achieving King's dream, but there is also more political division than in decades about whether changes to voting rights laws in jurisdictions across the country constitute an affront to civil rights. Combating election law changes they believe are discriminatory is at the top of the agenda of civil rights activists, but many of Republicans and Democrats who have historically come together to support continued federal vigilance over potentially discriminatory laws are divided. READ MORE: http://abcn.ws/1dpzMA9

BUZZ

BIDEN: 'NO DOUBT' SYRIAN REGIME BEHIND CHEMICAL ATTACK. Vice President Joe Biden yesterday said there's "no doubt" that Bashar al-Assad's regime is responsible for the recent chemical weapons attack on Syrian civilians, as the Obama administration weighs its response, ABC's MARY BRUCE reports. "There is no doubt that an essential international norm has been violated - violated. Chemical weapons have been used," the vice president told the American Legion National Convention in Houston. "And there is no doubt who is responsible for this heinous use of chemical weapons in Syria: the Syrian regime." "For we know that the Syrian regime are the only ones who have the weapons - have used chemical weapons multiple times in the past, have the means of delivering those weapons, have been determined to wipe out exactly the places that were attacked by chemical weapons," he continued. "And instead of allowing U.N. inspectors immediate access, the government has repeatedly shelled the sites of the attack and blocked the investigation for five days." http://abcn.ws/12IBNjT

ADMINISTRATION DRUMS UP CONGRESSIONAL SUPPORT FOR SYRIAN STRIKE. While President Obama considers options for responding to what they say was a chemical weapons attack in Syria, several senior administration officials are conducting a full-court press to drum up support for a military response, ABC's JOHN PARKINSON and ARLETTE SAENZ report. They are consulting with key members of Congress to keep them apprised on strings of intelligence as they are being developed and the possibilities that await the president's approval. Beyond the outreach from senior administration officials, ABC News has learned that in recent days Sen. John McCain, R-Ariz., has personally spoken with President Obama, his 2008 presidential campaign rival, to discuss America's response, according to an aide to McCain. McCain, who also connected with National Security Advisor Susan Rice, questioned whether an air strike would be effective and offered suggestions for additional actions the administration could take against the Syrian government. "Will those attacks just be a retaliation and [Syrian President Bashar al-Assad] basically goes on as normal?" McCain asked during an appearance on Fox News yesterday. "Or will those attacks degrade his capabilities, particularly his air capabilities, which you could do easily with standoff weaponry and start getting weapons that people need, Gen. Idris and his people need, in order to reverse the momentum on the battlefield.

- LAWMAKERS CONSULTED. Secretary of State John Kerry has also placed a number of calls to top members of committees with jurisdiction in the matter, including House Foreign Affairs Chairman Ed Royce, R-Calif., and Ranking Democrat Eliot Engel, D-N.Y. A spokesman for Royce said that the chairman "discussed the situation in Syria" with Kerry late Monday, but did not divulge details of the conversation. Kerry also connected with Senate Foreign Relations Chairman Bob Menendez, D-N.J., as did U.S. Ambassador to the United Nations Samantha Power, while the ranking Republican on the committee, Sen. Bob Corker, R-Tenn., spoke to "administration officials" numerous times throughout the past several days, according to an aide. Sen. Carl Levin, D-Mich., the chairman of the Senate Armed Services Committee, said he was briefed by the administration. And, "senior" Defense Department officials have reached out to House Armed Services Chairman Buck McKeon, R-Calif., and ranking Democrat Adam Smith of Washington state to discuss the crisis, according to committee aides. A congressional source said House Minority Leader Nancy Pelosi, D-Calif., "was personally briefed by National Security Advisor Susan Rice late yesterday [Monday]." Tony Blinken, the Deputy National Security Advisor, also briefed House Democratic Whip Steny Hoyer, the No. 2 Democrat in the lower chamber, as well as House Majority Leader Eric Cantor, R-Va.

-MAKING THE CASE FOR CONGRESSIONAL AUTHORIZATION. Rep. Justin Amash, demanded that the president first acquire congressional authorization before going forward with any sort of military strike. Amash, a second-term Republican from Michigan, asked Boehner to call the House of Representatives back into session for a debate and vote on authorization, and asserted that a strike authorized by the president without congressional authorization is "unquestionably unconstitutional" and "illegal," citing the War Powers Act. Rep. Thomas Massie, R-Ky., agreed - pointing to Article 1, Section 8 of the Constitution, which gives Congress - not the President - the power to declare war. Despite U.S. military action in more than a dozen theaters of conflict over the past 70 years, the United States has not formally declared war on any country since World War II, when it declared war on Bulgaria, Hungary and Romania on June 5, 1942. Congress last authorized U.S. military combat for Operation Iraqi Freedom in 2003, although the president has authorized military action against countries such as Libya as recently as 2011.

OUTGOING DHS SECRETARY JANET NAPOLITANO WARNS OF 'SERIOUS' CYBER ATTACK. The outgoing Homeland Security Secretary has a warning for her successor: A massive and "serious" cyber attack on the U.S. homeland is coming, and a natural disaster - the likes of which the nation has never seen - is also likely on its way, according to ABC's MIKE LEVINE. So prepare, and bring "a large bottle of Advil," Janet Napolitano told her yet-to-be-named replacement in a farewell address yesterday. "Many things still need tending, and my successor will most certainly have a full plate on his or her hands," said Napolitano, who leaves her post next week after more than four years at the helm of the Department of Homeland Security. Napolitano said she faced "many challenges" during her tenure at DHS, from the H1N1 flu pandemic in 2009 to the Deepwater Horizon oil spill in 2010 and Hurricane Sandy in 2012. DHS - backed by the Federal Emergency Management Agency, the U.S. Coast Guard and other federal departments and agencies - led the federal government's response to such disasters. During Napolitano's tenure, her department managed 325 federally declared disasters, and issued more than 60 emergency declarations, she said at the National Press Club in Washington. http://abcn.ws/12HX8Kq

THE COMPLICATED LEGAL BACKSTORY OF TERRY MCAULIFFE'S FORMER CAR COMPANY. For an upstart electric-car company with big ambitions, its ties to Virginia gubernatorial candidate Terry McAuliffe have been both a blessing and a curse, ABC's CHRIS GOOD reports. The company, GreenTech, is now front and center in Virginia's 2013 race for governor, and its critics are raising questions about political favoritism, national-security risks, and the government's role in foreign investments-unwelcome attention for the struggling firm. McAuliffe defended his role in the company in a recent op-ed. But troubles began for two GreenTech executives before McAuliffe became its chairman and well before he launched his Democratic bid for governor. In 2009, months before McAuliffe bought 25 percent of GreenTech and became chairman, two top executives were embroiled in a lawsuit that was covered in local press and detailed in a federal judge's advisory opinion. Not only was the future CEO of GreenTech, Xiaolin "Charles" Wang, embroiled in a dispute with a business partner not long before McAuliffe got involved, a federal judge said Wang took actions of "dubious legality" in issuing stock in connection with a similar company, Hybrid Kinetic Automotive Corp. While all of that long predated McAuliffe's involvement in GreenTech, and while he left GreenTech as chairman last year, the man who is now hoping to be governor of Virginia has acknowledged joining the executives' new venture despite knowing about some of the past legal troubles. BACKSTORY: http://abcn.ws/12KlVNS

ON VIDEO PRESIDENT FORD RECOUNTS ASSASSINATION ATTEMPT. A cult member scheming to assassinate the President of the United States may sound like the plot for a fictional thriller, but it's actually a rediscovered page out of American history books made available to the public for the first time, ABC's ALISA WIERSEMA notes. Footage of President Ford's testimony against his failed assassin, Lynette "Squeaky" Fromme, was released Monday after being sealed for nearly 38 years - thanks to a motion filed by the Eastern District Historical Society, a group in Sacramento, Calif. The testimony marked the first time in history that a sitting American president was called to testify in a criminal trial. Throughout the nearly 20-minute-long testimony, Ford calmly gestures and sips water as he responds to questions about the events leading up to the shocking incident. Ford said he noticed a person in a "brightly colored dress" among a crowd of bystanders on his way to the state Capitol in Sacramento. He also noted that the person, who would later be identified as Fromme, "appeared to want to either shake hands or speak, or at least wanted to get closer" to him. When the woman moved toward him, Ford stated that he assumed she wanted to shake hands, but quickly realized his error. "As I stopped, I saw a hand come through the crowd [and] in the hand was a weapon," Ford said. http://abcn.ws/16OztZB

IN CASE YOU MISSED IT

ABC'S DAVID FORD JOINS FUSION. Fusion, the joint venture of ABC News and Univision, announced yesterday that ABC's David Ford is joining the fledgling network. Acting President for Fusion, Beau Ferrari, sent the following note about David's hire: "I am delighted to tell you that David Ford is joining Fusion as our Vice President for Corporate Communications. He will be based at our Miami headquarters starting in mid-September. David will oversee all external and internal communications for Fusion and serve as a primary point of contact with key members of the media. David has forged important relationships inside both ABC and Univision. He joins us from the ABC News PR team, widely regarded as one of the finest, most effective, and strategic in the business. And he has worked closely with the outstanding communications teams at Univision since Fusion's earliest days. Most recently, David oversaw media relations for ABC's flagship evening newscast 'World News with Diane Sawyer,' which is having its best season in five years, as well as the network's Washington Bureau and award-winning investigative team led by Brian Ross." http://abcn.ws/14B0iRr

WHO'S TWEETING?

@RichardHaass: smart to keep strikes vs #syria limited in aim, punitive rather than ambitious, coercive so that US keeps initiative http://nyti.ms/1dn6jGY

@gregmcrc: Amazing how many Democrats in Congress have 180'd since Bush years-now support a 3rd war abroad. #tcot #teaparty #gop

@PBS: EXCLUSIVE/Tonight: The @NewsHour's @JudyWoodruff & @gwenifill interview Pres.Obama @ the White House.Tune in tonight! http://ow.ly/okVjU

@Yahoo: Here are 10 facts you should know on the 50th anniversary of Dr. Martin Luther King Jr.'s "I Have a Dream" speech: http://yhoo.it/19YC2Nu

@rickklein: Jesse Jackson: "we've got the dream, but we need the budget… that's what the president has no one else can offer." http://www.washingtonpost.com/politics/50-years-after-march-obama-aims-to-define-his-role-in-a-new-front-in-the-fight-for-equality/2013/08/27/617d9f4c-0e56-11e3-bdf6-e4fc677d94a1_story_3.html …