Donald Trump and Hillary Clinton scored huge victories Tuesday that bring them closer to a monumental duel for the White House in the fall.
Trump's political strength was on display with a clean sweep of races in Maryland, Delaware, Pennsylvania, Connecticut and Rhode Island. Clinton delivered big wins in Maryland and Pennsylvania -- the biggest prizes of the night -- along with Delaware and Connecticut. Bernie Sanders came out on top in Rhode Island.
For Trump, the wins -- following a massive victory last week in New York -- move him significantly closer to the 1,237 delegates he needs to win the nomination outright heading into the convention in July. In the process, he inflicted serious blows on the legitimacy of claims by rivals Texas Sen. Ted Cruz and Ohio Gov. John Kasich that he should be deprived of the GOP nomination.
"This, to me, was our biggest night," Trump said in his victory speech. "I consider myself the presumptive nominee."
Clinton's big wins, meanwhile, help bolster her campaign's argument that it is time for Sanders to make a decision to stop personal and political attacks on the former secretary of state that could weaken her ahead of a showdown in November with Republicans.
She climbed on stage to cheers in her election-night headquarters in Philadelphia, the city that will host the Democratic National Convention this summer.
"With your help, we are going to come back to Philadelphia for the Democratic National Convention with the most votes and the most pledged delegates," Clinton declared. "And we will unify our party to win this election and build an America where we can all rise together, an America where we lift each other up instead of tearing each other down."
Clinton foreshadowed the clash to come against Trump.
"The other day, Mr. Trump accused me of playing, the, quote, woman card. Well, if fighting for women's health care and paid family leave and equal pay is playing the woman card, then deal me in."
Not backing down
But Trump and Clinton's challengers showed no sign of backing down Tuesday despite a rapidly narrowing path to the nomination.
Cruz, speaking before polls closed -- in a clear sign that he expected a bad night -- slammed the media for what he said was a premature judgment that the general-election nominees would be Clinton and Trump. He branded them "New York liberals."
But he predicted things would change next week.
"I've got good news for you tonight, this campaign moves back to more favorable terrain," Cruz told a crowd in Indiana.
Sanders also spoke early in West Virginia, which holds its primary next month, and made clear he is not leaving the race. He said he had a "significantly larger" lead in match-up polls over Trump than Clinton --- hinting that he would press on with his bid to convince superdelegates to back him instead of Clinton at the Democratic National Convention in July.
He said he was winning independent voters and some Republicans and added: "That is a point that I hope the delegates to the Democratic convention fully understand."
Battle for delegates
Republicans are battling for 172 delegates, and Trump went into the night needing to win 58% of delegates available in remaining primaries to capture the nomination, according to CNN estimates.
The always complicated science of delegate allocation will be even more arcane than usual because of Pennsylvania's one-of-a-kind system, where 54 of the state's 71 delegates are unbound. That means they can vote for who they like in the first round of voting in the Republican convention in Cleveland in July and will be a key voting bloc if Trump doesn't win 1,237 delegates.
In the event that Trump falls short of that magic number, unbound delegates could be crucial in deciding the fate of the Republican nomination. Cruz has mounted an especially sophisticated operation to fill delegate slates with sympathetic activists who could desert Trump in later rounds of voting in Cleveland should the billionaire fall short on the first ballot.
Trump campaign manager Corey Lewandowski offered a preview earlier Tuesday of how Trump will capitalize on his East Coast victories to build pressure on Republican rivals Cruz and Kasich to get out of the race.
"What it comes down to is after tonight, Ted Cruz is mathematically eliminated from being the Republican nominee on the first ballot. John Kasich is already mathematically eliminated. So in order to unite the party after tonight, Ted Cruz and John Kasich should support Donald Trump so that we are clearly focused on .... putting (a) Republican back in the White House," Lewandowski told CNN's Jake Tapper on "The Lead."
Clinton banking on a big night
In the Democratic race, Clinton is banking on a big night to build on her resounding success in New York, which stunted Sanders' momentum and left the senator -- for all his fundraising muscle and large rallies -- fending off calls from Clinton supporters to fold his campaign so that she can start exclusively targeting Republicans.
Sanders and Clinton are competing for 384 pledged delegates on Tuesday. Clinton currently leads Sanders by 253 pledged delegates, according to a CNN estimate, and is dominating the count among superdelegates -- party officials and activists who also have a convention vote.
At her victory speech, Clinton extended an olive branch to Sanders in an apparent effort to begin the process of unifying the Democratic Party behind her candidacy.
"I applaud Sen. Sanders and his millions of supporters for challenging us to get unaccountable money out of politics and putting greater emphasis to closing the gap of inequality," she said. "I know together we will get that done."