A big night for Clinton as she wins Ohio, Florida and N.C.

WEST PALM BEACH, Fla. - Tuesday was always supposed to be one of the most important nights in the Democratic presidential primary race, but for Hillary Clinton, it was even bigger than she and her team expected.

Clinton's victories in Ohio, Florida and North Carolina put her firmly on course to defeat her primary rival, Sen. Bernie Sanders of Vermont. As the results were announced on Tuesday evening, she took the stage before a boisterous crowd of supporters here and seemed to pivot towards the Republican frontrunner, Donald Trump, who also won in Florida.

"We are moving closer to securing the Democratic Party nomination and winning this election in November!" Clinton declared.

Clinton came into the presidential race as the overwhelming frontrunner. After faltering in the early states, she began to pull ahead, with a massive victory in South Carolina on Feb. 27. She followed that win with a string of victories on "Super Tuesday," March 1. Those wins had a campaign source predicting to Yahoo News that Clinton's delegate lead over Sanders would be "effectively insurmountable" once this evening's votes were counted. Sanders' team also knew this evening's numbers would be crucial, and in early strategy sessions, they cited March 15 as a turning point, after which they would know whether or not his underdog bid was truly viable.

It looked as if Sanders might prove the Clinton campaign's bullish prediction wrong after he won a stunning upset in Michigan on March 8, but Clinton's victories on Tuesday helped her stop Sanders' momentum and establish a seemingly unbeatable lead.

Though Clinton was expected to win the primaries in North Carolina and Florida on Tuesday, polls showed her potentially losing in Ohio, Arizona, Missouri and Illinois. Even if Sanders had won all of the states that were in play on Tuesday, he would still have faced an uphill battle. However, by taking Ohio, Clinton definitively pulled ahead.

Though the results in Arizona, Missouri and Illinois still had not been projected at the time she spoke, Clinton pointed out that her trio of victories had allowed her campaign to "add to our delegate lead to roughly 300."

"I'll tell you, this is another Super Tuesday!" Clinton said.

After congratulating Sanders "for the vigorous campaign he's waging," Clinton turned to Trump, framing the election as "one of the most consequential campaigns of our lifetimes." She specifically criticized Trump's positions, including his calling for a ban on Muslim immigration, and took a shot at his campaign slogan, "Make American Great Again."

"We can't lose what made America great in the first place," Clinton said.

Sanders took the stage shortly after Clinton's appearance in Florida and addressed more than 7,000 of cheering supporters in a convention center in Phoenix with his usual stump speech. The 74-year-old senator mentioned raising the minimum wage, getting money out of politics, fixing free trade deals and reforming the criminal justice system, among other typical stump-speech issues.

What Sanders didn't mention were the five states that voted in the Democratic primaries Tuesday night, and what the results meant for his viability as a candidate. This was in contrast to Sanders' election night appearance on Super Tuesday, when he explicitly downplayed his mixed showing and reassured his supporters he would take the fight to "every" state. In contrast with most election night gatherings, there were no TVs showing primary results in Phoenix, so Sanders' supporters were not shown Clinton's wins racking up in the background as the evening progresses. Arizona's Democrats vote next Tuesday, and Sanders is expected to do well in the state.

"The reason we have done as well as we have, the reason we have defied all expectations, is that we are doing something very radical in American politics: We are telling the truth!" Sanders said. No major cable network carried his speech, which coincided with Ohio Gov. John Kasich's remarks and later, as Sanders continued speaking, with Donald Trump's victory speech. The senator urged Arizonans to show up at the polls for him next week at the end of his address.

Sanders' top advisers have stressed that the senator will continue his well-funded campaign until the end of the primaries, and last week's surprise win in Michigan appeared to breathe new life into Sanders' bid. Sanders could still win Illinois and Missouri on Tuesday, but Clinton's strong showing in North Carolina, Florida and Ohio dim his chances of becoming the Democratic nominee. Sanders had hammered Clinton on her past support for free-trade deals, but she still pulled out a win in Ohio.