Here are key moments from Democratic presidential candidates Hillary Clinton and Bernie Sanders's speeches, as results from Super Tuesday elections rolled in on March 1. (Sarah Parnass/The Washington Post)

MIAMI — Former secretary of state Hillary Clinton racked up a string of wins across the south on Super Tuesday, as she widened her lead in the race for the Democratic presidential nomination over rival Vermont Sen. Bernie Sanders.

Clinton was projected to win in seven states--Alabama, Arkansas, Georgia, Tennessee, Massachusetts, Virginia and Texas, where the largest number of delegates were at stake. The narrow win in Massachusetts was a particular prize as Sanders has run strongly in other New England contests.

Speaking in Florida, Clinton signaled that she is already looking past the Democratic nominating process. With only a brief mention of Sanders, she instead targeted most of her remarks at the night’s big Republican winner: Donald Trump.

“America never stopped being great. We have to make America whole,” she said, referring to Trump’s slogan, ‘Make America Great Again.’ “It’s clear tonight that the stakes of this election have never been higher. And the rhetoric we’re hearing on the other side has never been lower.”

Sanders won his home state of Vermont, Oklahoma, Colorado and Minnesota.

More Democratic delegates were up for grabs on Tuesday than on any other day of the nominating contest.

The major contests came on the heels of Clinton’s trouncing of Sanders by nearly 50 percentage points in South Carolina on Saturday. That win revealed an overwhelming advantage for Clinton among African American voters, an advantage that she built on to sweep states with large minority populations on Tuesday.

But in a speech in front of an adoring crowd in his home state of Vermont, Sanders vowed that he will press forward and remain in the Democratic race into the summer.

“We have come a very long way in 10 months,” he said. “At the end of tonight, 15 states will have voted. Thirty-five states remain. 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.”

Exit poll data in one key state, Virginia, showed a dominating win for Clinton. Virginia is a swing state important to Democrats’ hopes of retaining the White House, where Clinton ally Terry McAuliffe serves as governor.

The polling data showed she won in every region of the state, as well as among both men and women, whites and blacks and in every age group older than 30. As he has in previous contests, however, Sanders bested Clinton among young voters.

Virginia primary exit poll results

According to Edison Media Research, Democratic turnout was down from 2008 in the Super Tuesday primaries, while Republican turnout was up.

Clinton’s recent wins in South Carolina and also the Nevada caucuses have allowed her to stabilize her campaign after her dramatic loss to Sanders in the New Hampshire primary.

Sanders has mounted an unexpectedly tough challenge to Clinton and he continues to draw large crowds and rake in campaign contributions with an economic message that has promised to lift the middle class and close the gap between rich and poor.

Still, after her recent victories, Clinton this week has begun to pivot to Trump.

Taking questions from traveling reporters for the first time in months, Clinton said while campaigning in Minneapolis that Trump appears to be “on the path” to the GOP nomination.

“I’m just speaking out against bigotry and bullying wherever I hear it,” said Clinton, who was campaigning with Minnesota Gov. Mark Dayton (D). “And I hear a lot of it from the Republican candidates.”

Clinton is spending her election eve in Florida, hosting a campaign victory party in a state that will be politically important later in the month. Florida will award 214 delegates on March 15.

Sanders, meanwhile, cast his vote early Tuesday at a polling station in Burlington, Vt., the city where he served as mayor in the 1980s.

“I will tell you: After a lot of thought, I voted for me for president,” a smiling Sanders told one man after taking a selfie with him.

Sanders vowed that he would soldier on, regardless of how many delegates he wins Tuesday.

“This is a campaign that’s going to the Philadelphia convention in July,” he said.

Wagner reported from Essex Junction, Vt. and Helderman from Washington. Scott Clement and Juliette Eilperin in Washington; Katie Zezima in Houston; Patricia Sullivan in Arlington, Va.; Laura Vozzella in Richmond, Va. Abby Phillip in Minneapolis, Minn. and Miami; Anne Gearan and Paul Kane in Washington; Robert Costa in Atlanta; Jose A. DelReal in Nashville; Fenit Nirappil in Norfolk, Va.; Ed O’Keefe in Alcoa, Tenn.; and David Weigel in Castleton, Vt., contributed to this report.