Hillary Berns Sanders in all 5 states

Sen. Bernie Sanders

It was another big night in the race for the Democratic Party nomination, and front-runner Hillary Clinton faced strong challenges by rival Bernie Sanders in at least three of Tuesday's five presidential primaries.

With only 6 percent of the vote tallied in Ohio, AP and NBC called the election for Clinton.

"Because of all of you and our supporters across the country," said Clinton in her victory speech in West Palm Beach, Florida, "our campaign has earned more votes than any other candidate, Democrat or Republican ... and I want to congratulate Sanders for the vigorous campaign he is waging. ... Now today all of you voted to break down the barriers that hold us all back so that every one of us can share in the promise in America. ...

"Making differences in peoples lives comes first because Americans everywhere are hungry for solutions. Ask any parent. Nothing is more important than making sure that their kinds have a good school and teacher no matter what zip code they live in. They deserves a president who understands when we invest in our children's education, we are investing in all of our future. ... Tonight it is clearer than ever that this may be one of the most consequential campaigns of our lifetimes. Now I know that easy decisions don't make it to the president's desk, only the thorniest problems. I saw the decision Obama had with helping to save the auto industry, the affordable care act and so many more. Our next president needs to be ready for three big tasks: can you make positive differences in peoples lives, can you keep us safe, and can you bring our country together again.

"Grandparents who worry about retirement need someone who will protect and expand social security for those that need it the most, not cut or privatize it.

"The second big task for our next president is keeping us safe. We live in a complex and dangerous world. Protecting America's security cannot be an afterthought. Our commander in chief must protect our country, not embarrass it; engage our allies, not alienate them; defeat our adversaries, not embolden them. When Trump embraces torture, that doesn't make him strong, it makes him wrong. And yes, our next president must bring our country together so we can all share in the promise in America. We should be breaking down barriers, not building up walls. To be great we cannot be small, we cannot lose what made America great in the first place."

Clinton had a clear advantage in North Carolina and Florida, but Sanders planned to give her stiff competition in Illinois, Missouri and Ohio. The primaries came just one week after Sanders enjoyed an upset victory against Clinton in Michigan.

Florida was the largest prize Tuesday evening, as the winner-take-all state offers 246 Democrat delegates.

Clinton had more than half the delegates needed to win the nomination, mostly because superdelegates had largely chosen to align behind her. To get the Democratic Party nomination, a candidate must win 2,383 delegates. As of Tuesday, 2,950 were still available.

Sanders was under pressure to demonstrate his Michigan win was not a fluke. He needed to prevail with major wins in Missouri, Ohio and Illinois to prove he is still a viable contender for the nomination or face pressure to bow out of the race.

Clinton's Facebook page showed some eager future voters in North Carolina.

An emotional voter named Laura sent Clinton an email Tuesday morning:

I cast my ballot for you today in Missouri. It was such an emotional moment for me that I found myself in tears as I drove home from my polling place – tears of joy to have the opportunity to vote for you not only because you are going to be the first woman president, but because you are the right person for this country!! I believe in you and am so proud to watch you become the first woman president of the United States. Thank you.

The mother of Michael Brown, killed by police in Ferguson, Missouri, endorsed Clinton.