"Today, voters from the West Coast to the Gulf Coast to the heart of America stood up to say, 'Yes, we can,'" Obama said at a Virginia political dinner Saturday night. "We won in Louisiana, we won in Nebraska, and we won Washington state -- and we won north, we won south and we won in between. And I believe that we can win in Virginia on Tuesday if you're ready to stand for change."
Arizona Sen. John McCain and former Arkansas Gov. Mike Huckabee were locked in a close battle in Louisiana, which Huckabee later won. Huckabee also won in Kansas, while McCain took a tight race in Washington state, where Huckabee said he was not ready to admit defeat.
"We're looking at some legal issues. We're not ready to concede that one," Huckabee said, without going into specifics, according to The Associated Press.
While Super Tuesday voting may have cleared McCain's path to the GOP nomination, it also exposed just how close the race is between Obama and Clinton, who entered Saturday's four Democratic contests separated by less than 100 delegates, according to ABC News' Delegate Tracker.
A total of 158 Democratic delegates were at stake on Saturday between the Louisiana primary and caucuses in Nebraska, Washington and the Virgin Islands.
Obama won by large margins in the Saturday races. In the Nebraska caucuses, with 99 percent of precincts reporting, he held a 68-32 percent advantage. The margin was similar in the Washington state caucuses, with Obama claiming 68 percent of the vote with 94 percent of the precincts reporting. The race was a bit closer in the Louisiana primary, where Obama was the projected winner with 53-39 percent of the vote with 74 percent of precincts reporting. Obama also claimed the Virgin Islands caucuses.
The winner of the Democratic party, who will make history as either the first black or first female presidential candidate from a major party, will need 2,025 delegates to claim the nomination at the party's convention in Denver this August.
Obama was expected to do well in Saturday's caucuses in Washington, where the Illinois senator spent a significant amount of time this week and picked up the support of the Seattle mayor and state governor. Clinton, however, also had visited the Pacific Northwest this week and had support from both of Washington's U.S. senators, who will serve as superdelegates at the Democratic national convention.
Clinton actually may have performed better than expected in Louisiana, winning the majority of white voters in the primary. She could not, however, overcome the black vote. In Louisiana, according to ABC News analysis of exit polls, four in 10 voters are black, and black voters supported Obama 4-1 over Clinton.
Young voters, who typically have favored Obama, were in short supply, with under-30s accounting for just under one in 10 voters, a low proportion in the 2008 Democratic primaries to date. Nearly a quarter of voters, by contrast, are 65 and older.
The top issue in Louisiana, as it has been elsewhere, was the economy. Nearly half of Democrats called it the single most important issue in their vote; about three in 10 said it was the war in Iraq; about a quarter, health care.
Earlier Saturday, Huckabee won the Kansas Republican caucuses.
Huckabee may have drawn first blood in the series of post-Super Tuesday contests, but McCain remains the formidable frontrunner for the Republican nomination.
"I didn't major in math," Huckabee told a conservative conference in Washington on Saturday. "I majored in miracles, and I still believe in them, too."
Huckabee Looks for 'Miracle'
The former governor has resisted calls to leave the race given that McCain has taken a near-insurmountable delegate lead.
On Saturday Huckabee declined a public request by Texas Gov. Rick Perry that he drop his bid and get behind McCain's campaign.
The departure of former Gov. Mitt Romney from the GOP field on Thursday leaves just McCain, Huckabee, and Rep. Ron Paul, R-Tex., in the race.
Viewed as more conservative than McCain, Huckabee could continue to draw voters unhappy with McCain's policies. ABC News' preliminary exit polling in Louisiana, the other state where GOP delegates are in play, found that more than half of Republican primary voters described themselves as evangelical Christians.
"There are only a few states that have voted. Twenty-seven have not. People in those 27 states deserve more than a coronation, they deserve an election," said Huckabee.
Even Paul has cut staff in the face of McCain's lead, and some political pundits have speculated Huckabee's persistence may have more to do with gaining a spot on the McCain ticket than winning the nomination at this point.
McCain's victories Tuesday prompted Romney, the former Massachusetts governor, to suspend his campaign, an announcement he made to party loyalists at the Conservative Political Action Conference. In McCain's speech to the group, the new frontrunner began working a theme of party unity while fending off criticisms from some about the war hero's conservative credentials.
Gearing Up for the Long Haul
The post-Super Tuesday campaign week included a pair of buzzmaking storylines for the Democrats, one about the candidates' financial strength going into what will almost certainly be a long race and the other about a political pundit's off-color remark.
The Obama campaign, which logged huge fundraising numbers in the most recent reporting quarter, announced that it had collected $7.5 million in roughly 48 hours after the Super Tuesday polls closed.
On the Clinton side, the campaign first announced that the candidate had spent $5 million of her own money to help cover pre-Super Tuesday expenses, including advertising.
The campaign also said that high-level advisers would be going without pay in the month of February, but that notion was short-lived, if not a campaign stunt, as reported by ABC News' Kate Snow.
By the end of the week, the Clinton camp boasted that it had raised $7.5 million since Feb. 1 – including $6.4 million online in the 30 hours after polls closed Tuesday.
The other campaign story making headlines late this week was an off-color comment made by MSNBC's David Shuster, who used the word "pimp" to describe how Hillary Clinton and former President Bill Clinton have enlisted their daughter Chelsea to work on the campaign trail.
Shuster was suspended by the network and offered an apology after Clinton's campaign suggested the angry candidate may pull out of the network's debates. Clinton responded today directly to the controversy, which Obama's campaign called deplorable.
"I am a mom first and a candidate second," Clinton told reporters after a rally at the University of Maine in Orono. "I found the remarks incredibly offensive. I can take whatever comes my way, that's part of what I signed up for as a candidate as an office holder, but I think that there's been a troubling pattern of comments and behavior that has to be held accountable." Clinton also sent a formal letter to the network to express her disgust.
Maine will holds its Democratic caucuses Sunday, with 24 delegates at stake. From there, it's on to the Mid-Atlantic Tuesday, with voters in Maryland, Virginia and the District of Columbia voting for a combined 175 delegates.
One of the next key dates will be March 4, when 380 delegates will be at play in contests in critical states like Ohio and Texas.
ABC News' Polling Director Gary Langer contributed to this report.