In the Democratic race, there were further big wins for Hillary Clinton, with only one state for Bernie Sanders
Republican front runner Donald Trump has told his rivals: "It's over", after scoring landslide victories in five northeastern US state primaries.
The New York real estate baron called himself "the presumptive nominee", as he celebrated knockout blows in Connecticut, Pennsylvania, Maryland, Rhode Island and Delaware.
In the Democratic race, front runner Hillary Clinton swept Maryland, Delaware, Pennsylvania and Connecticut.
Her challenger, Vermont Senator Bernie Sanders, walked away with a consolation win in Rhode Island.
Mrs Clinton and Mr Trump are gearing up for a possible showdown against one another in November's White House election.
Victoria Jones, Chief White House Correspondent for Talk Media News, told Newstalk Breakfast that Trump has "not done it yet despite what he says.
"He needs to win Indiana next week - that's the key - and Indiana is a more conservative state than the five states that voted yesterday," she explained.
At her Tuesday night victory rally in Philadelphia, Mrs Clinton assailed the property magnate.
"Now, the other day Mr Trump accused me of playing the, quote, woman card," the former Secretary of State, US senator and first lady told her supporters.
"Well if fighting for women's healthcare, paid family leave and equal pay is playing the 'woman card', then deal me in!"
In another jab, she went on to envisage an America where "love trumps hate".
At his victory rally in New York, Mr Trump said Mrs Clinton was a "flawed candidate", whom he would beat "so easily".
"I call her crooked Hillary," he said. "She's crooked. She'd be a horrible president. She knows nothing about job creation.
"Her husband signed (free trade agreement) NAFTA, which destroyed this country economically."
Mr Trump called on his Republican rivals, Texas Senator Ted Cruz and Ohio Governor John Kasich, to drop out and unite behind him.
He branded Mr Kasich "one in 46", a reference to his sole primary victory in his home state.
Mrs Clinton, who aims to be the first US female president, now has 90% of the delegates she needs to win the Democratic nomination.
But Mr Sanders has vowed to fight on until California's primary in June.
Mr Trump is the only Republican who can reach the 1,237 delegates needed to be anointed as that party's White House nominee.
But Mr Cruz has been successfully manoeuvring to win over delegates who might side with him.
He hopes to pounce if Mr Trump cannot accumulate the magic number on a first ballot at the Republican conference in Cleveland, Ohio.
There were 384 Democratic delegates up for grabs on Tuesday, and 172 for Republicans.