Former secretary of state Hillary Clinton triumphed over Vermont Senator Bernie Sanders on Super Tuesday, winning in eight out of the 11 states and one territory that went to the polls to choose their Democratic nominee for the November presidential election.
But Mr Sanders put up a decent fight with four wins - in his home state of Vermont and the closely contested states of Oklahoma, Colorado and Minnesota.
The wins were significant for Mr Sanders, said pollster John Zogby of Zogby Analytics: "If he can win Minnesota or Colorado, then he is well on his way to friendlier turf."
He added that the left wing of the party, which generally backs Mr Sanders, has historically done well in big states like New York and California, which will come later in this primary process.
Super Tuesday - the most important day of voting in the candidates' nomination race - has by no means handed Mrs Clinton the "coup de grace she hoped to deliver", said Dr Daniel Franklin, an associate professor of political science at Georgia State University.
Even though she won in Texas, Georgia, Tennessee, Alabama, Virginia, Arkansas, Massachusetts and American Samoa, there are chinks in her armour, said experts.
• Caucuses in Kansas, Kentucky and Maine, and primary elections in Louisiana on Saturday and Puerto Rico on Sunday.
• The next really big tests come in primaries in Michigan, Mississippi and Idaho next Tuesday, and Florida, Illinois, Missouri, North Carolina and Ohio on March 15. • Senator Marco Rubio needs a win in his home state of Florida; anything less and he could be out of the nomination race.
• Mr John Kasich needs wins in Ohio, where he is governor, and neighbouring Michigan. Wins by Mr Donald Trump, especially in Ohio, would probably be a knockout blow for him.
• Caucuses in Kansas and Nebraska and a primary in Louisiana on Saturday, and caucuses in Nebraska on Saturday and Maine on Sunday.
• Primaries will be held in Michigan and Mississippi next Tuesday. Florida, Illinois, Missouri, North Carolina and Ohio will hold primaries on March 15.
• Wins by Mrs Hillary Clinton in Florida, North Carolina, Michigan and Illinois could be fatal to Senator Bernie Sanders' campaign.
"The fact that she cannot win outside of states with large minority populations means she has a weakness that must be addressed; if not now, by the time of the general election," said Dr Franklin.
Mrs Clinton achieved convincing wins in southern states like Georgia (71.2 per cent versus 28.3 per cent) and Alabama (77.8 per cent versus 19.2 per cent), while Mr Sanders achieved a similar wide margin only in his home state of Vermont (86.2 per cent to Mrs Clinton's 13.6 per cent).
"I still don't think Sanders can win. But he has reason to continue, and the longer this goes on, the weaker Hillary Clinton looks," Dr Franklin added.
However, Mrs Clinton has gained a sizeable number of delegates, who will pick the party's nominee at its national convention in July.
A Democratic candidate must gain 2,383 out of a total of 4,763 delegates available to clinch the party's nomination.
After Super Tuesday, Mrs Clinton has about 1,000 delegates, compared with Mr Sanders' 371, according to calculations by political website RealClearPolitics.
This count includes super-delegates, who are elected officials and notable party members, who have generally endorsed Mrs Clinton.
In her victory speech, Mrs Clinton said she would not take voters for granted. "We are going to work for every vote and we will need all of you volunteering, contributing, talking to your friends and neighbours, because this country belongs to all of us," she said in Florida, which casts its vote for a Democratic candidate on March 15.
Over in Vermont, playing to his home crowd, Mr Sanders said he was proud to "bring Vermont values all across the country".
"In Vermont, billionaires do not buy town meetings, and in America we are going to end a corrupt campaign finance system," said Mr Sanders, once again pounding away at one of his key election issues.
He assured supporters his campaign would continue, and Super Tuesday was but one part of the race to the White House.
"At the end of tonight, 15 states will have voted, 35 states will remain," said Mr Sanders. "Let me assure you that we are going to take our fight for economic justice, for social justice, for environmental sanity, for a world of peace to every one of those states."