Donald Trump has won presidential primaries in all five US states that voted on Tuesday, while Hillary Clinton triumphed in four out of five.
Mr Trump called himself the Republican “presumptive nominee” after victories in Connecticut, Delaware, Maryland, Pennsylvania and Rhode Island.
The results bring him closer to the number of delegates he needs before the party’s national convention in July.
For the Democrats, Mrs Clinton was denied a clean sweep by Bernie Sanders.
The Vermont senator won in Rhode Island and vowed to fight to the end of the primaries process.
Speaking at the Philadelphia Convention Center after securing the four other states, Mrs Clinton said her campaign was setting “bold, progressive goals” to improve lives in the US.
“We believe in the goodness of our people and the greatness of our nation,” she said.
After his sweep of the five states, Mr Trump said of the battle for the Republican nomination: “It’s over. As far as I’m concerned, it’s over.”
He told supporters in New York he would not moderate his policies if elected president.
He said: “You know I went to the best schools. I’m like a very smart person. I’m going to represent our country with dignity and very well.
“But I don’t really want to change my personality. You know, it got me here.”