Trump rolled up victories over rivals John Kasich and Ted Cruz in Pennsylvania, Maryland, Connecticut, Rhode Island and Delaware, with a margin of victory rivaling that in his home state of New York a week ago.
Democratic front-runner Hillary Clinton, already in control of the Democratic race, defeated challenger Bernie Sanders in Maryland, Delaware, Pennsylvania and Connecticut.
But in a surprise, Sanders was projected to have won Rhode Island.
In a speech and news conference at Trump Tower in New York, Trump said it was time for Cruz and Kasich to get out of the Republican race so the party can begin to unify behind him ahead of the Nov. 8 presidential election to succeed Democratic President Barack Obama.
"I consider myself the presumptive nominee," he said, adding later: "As far as I'm concerned, this thing is over."
For the Republicans, the Northeastern battles set the stage for a potentially pivotal primary contest next week in Indiana, where Trump has a small lead and got an endorsement from former Indiana University basketball coach Bobby Knight.
Clinton, in a victory speech in Philadelphia, took aim at Trump for accusing her of trying to "play the woman card" in seeking to become the first female U.S. president.
"Well if fighting for women's healthcare and paid family leave and equal pay is playing the woman card, then deal me in," she said to cheers.
Republican U.S. presidential candidate Donald Trump speaks to supporters during his five state primary night rally in New York City, U.S., April 26, 2016. REUTERS/Lucas Jackson |
'NO PATH TO VICTORY'
Although the race remains fluid, Trump's wins made it less likely that Republicans would choose their nominee at a contested convention in July in Cleveland, an outcome seen by Cruz and Kasich as their only chance at the nomination.
"They should drop out because frankly they have no path to victory," Trump told a Time interviewer at a magazine event in New York honoring influential Americans.
Cruz, already looking ahead to Indiana's Republican primary on May 3, addressed a crowd in that state just as polls were closing in the Northeastern states.
"I got good news for you: Tonight, this campaign moves back to more favorable terrain," the U.S. senator from Texas said in Knightstown, Indiana, inside the high school gymnasium made famous by the underdog movie, "Hoosiers."
An anti-Trump group called #NeverTrump formed by establishment Republicans said Trump's path to getting the 1,237 delegates he needs for the nomination remained narrow.
"And he just left the most favorable part of the map for him in the Northeast. Moving west, his ability to keep pace becomes more difficult," the group said.
A total of 118 pledged Republican delegates were at stake in addition to 54 unbound Pennsylvania delegates.
Cruz and Kasich, the Ohio governor, have formed an anti-Trump alliance in an effort to stop him from reaching a first-ballot victory at the July convention.
Democratic U.S. presidential candidate and U.S. Senator Bernie Sanders speaks to his supporters during his five state primary night rally in Huntington, West Virginia, U.S., April 26, 2016. REUTERS/Marcus Constantino |
APPEAL FOR UNITY
Clinton's strong showing in the Democratic race added to the pressure on Sanders to get out of the race or ease his criticism of her.
In her victory speech, Clinton gave a nod to Sanders and spoke of the need for party unity.
"Whether you support Senator Sanders or you support me, there is much more that unites us than divides us," she said.
Clinton reached out to a wide spectrum of voters, asking for support "if you are a Democrat, an independent or a thoughtful Republican."
The former secretary of state had an almost insurmountable lead of 275 pledged delegates heading into Tuesday's contests, and Senate Democratic leader Harry Reid told reporters he did not think Sanders, a U.S. senator from Vermont, had a realistic path to winning the nomination.
Sanders, speaking to a big crowd in Huntington, West Virginia, showed no signs of getting out of the race and said he was shedding light on inconvenient truths about how hard life was these days for some Americans.
"The reason that we are generating this enthusiasm is because we are doing something very unusual in contemporary politics. We are telling the truth," he said.
(Additional reporting by Emily Stephenson, Jeff Mason, Alana Wise and Megan Casella in Washington; Writing by Steve Holland; Editing by Peter Cooney)