Hillary Clinton took full command of the Democratic presidential race on Tuesday as she rolled to major victories over Bernie Sanders in Texas, Virginia and across the South and proved for the first time that she could build a national coalition of racially diverse voters that would be crucial in the November election.
Based on results from Democratic primaries and caucuses in 11 states, Mrs. Clinton succeeded in containing Mr. Sanders to states he was expected to win, like Vermont and Oklahoma, and overpowering him in predominantly black and Hispanic areas that were rich in delegates needed for the Democratic nomination.
Mrs. Clinton, who also won Massachusetts and showed notable strength among Southern white voters, came away with a strong delegate lead over Mr. Sanders — notably larger than the one that Barack Obama had over her at this point in the 2008 presidential race.
“What a super Tuesday!” Mrs. Clinton declared to cheers at a victory rally in Miami. In her recent signature line mocking Donald J. Trump’s slogan, she said: “America never stopped being great. We have to make America whole — fill in what’s been hollowed out.”
“The rhetoric we’re hearing on the other side has never been lower,” she added. “Trying to divide America between us and them is wrong, and we’re not going to let it work.” As the crowd broke out in chants of “U.S.A.,” she said, “Whether we like it or not, we’re all in this together, my friends, and we all have to do our part.”
The contests on Tuesday were well suited to Mrs. Clinton’s strengths: her popularity with minority voters, her political kinship with Southern Democrats from her two decades in Arkansas, and her success in delegate-rich Texas in 2008. She won sizable victories in Arkansas as well as Alabama, Georgia and Tennessee, with especially big margins in counties with many blacks.
Mr. Sanders’s advisers, in turn, described Tuesday as their candidate’s most difficult moment on the primary calendar, given the diverse electorate, the relative lack of states with huge liberal populations, and the dearth of caucuses — a format that Mr. Sanders believes favors him. He won the caucuses in Colorado and Minnesota on Tuesday; Mrs. Clinton won earlier caucuses in Iowa and Nevada.
While even the poorest showing would not drive Mr. Sanders from the presidential race, his advisers said, Mrs. Clinton was already looking past her party rival on Tuesday to the leading Republican candidate, Mr. Trump, saying she was “very disappointed” that he initially refused to disavow support from David Duke, the former Ku Klux Klan leader.
“We can’t let organizations and individuals that hold deplorable views about what it means to be an American be given any credence at all,” Mrs. Clinton told reporters while campaigning at a coffee shop in Minnesota. “I’m going to continue to speak out about bigotry wherever I see it or hear about it.”
Mr. Sanders, who has also criticized Mr. Trump over the Duke endorsement, cast his ballot in the Vermont primary on Tuesday and held a victory party shortly after he was declared the winner there at 7 p.m. Choosing not to wait and see the results in other states, Mr. Sanders sounded defiant at times and philosophical at others as he spoke to a hometown crowd of cheering admirers near Burlington.