After Obama's win, Bill Clinton made matters worse for his wife, seemingly dismissing the Obama campaign's chances for victories by comparing him to a previous unsuccessful minority candidate. Clinton told ABC News' David Wright in Columbia, S.C.: "Jesse Jackson won South Carolina in '84 and '88. Jackson ran a good campaign. And Obama ran a good campaign here."
John Edwards' departure from the race left a two-person contest for the Democratic nomination leading up to Super Tuesday, when 22 states held contests with nearly 1,700 of the more than 4,000 delegates at stake. After all the buildup, though, when all the votes were counted there still was no clear winner.
Clinton and Obama traded Super Tuesday victories as energized Democratic voters turned out in record high numbers.
Obama won the most states, picking up victories in Illinois, Idaho, Colorado, Minnesota, Connecticut, Utah, North Dakota, Kansas, Delaware, Missouri, Georgia, Alabama and Alaska.
But Clinton won the delegate-rich states of California, New York, Massachusetts (despite Obama receiving the endorsement of Sen. Ted Kennedy and Caroline Kennedy), and New Jersey, in addition to wins in Arizona, Oklahoma, Tennessee, New Mexico, Arkansas, and American Somoa.
On the Republican side, Arizona Sen. John McCain, secured his status as the unstoppable GOP front-runner, although his last opponent, former Arkansas Gov. Mike Huckabee would not leave the race for another month.
After Super Tuesday, Clinton faced her toughest stretch of the campaign since the period before the initial loss in Iowa.
Patti Solis Doyle, Clinton's campaign manager who had been with her since she was first lady of Arkansas, resigned from the campaign.
In a note sent to the campaign staff, Solis Doyle said: "This has already been the longest presidential campaign in the history of our nation, and one that has required enormous sacrifices from all of us and our families."
She wrote that she has been "proud to manage this campaign, and prouder still to call Hillary my friend for more than 16 years. I know that she will make a great president."
Maggie Williams, Clinton's chief of staff when she was first lady and an African-American, took over as Clinton's campaign manager.
The Clinton campaign also announced that the candidate had loaned $5 million of her own money to her campaign, raising considerable questions about her ability to compete financially against an opponent who continued to raise record amounts through the spring.
Obama won 11 straight primaries or caucuses in Louisiana, Nebraska, Washington state, the U.S. Virgin Islands, Maine, Maryland, Virginia, Washington, D.C., Hawaii, Wisconsin and Rhode Island.
The streak included some of Obama's most impressive victories, including a 64-35 percent win in Virginia, 75-24 percent in his native Hawaii, and a 58-41 percent margin in Wisconsin.
In Wisconsin exit polls, Democrats identified Obama, not Clinton, as most likely to win in November and it was one of the few times Clinton struggled to hold on to the support of some of her core groups -- white women, less-educated and lower-income voters.
As the losses kept coming, calls for Clinton to withdraw from the race began to grow louder, but the former first lady vowed to fight on in Texas and Ohio, which both held contests March 4.