By Emily Stephenson
A promise that US Republican front-runner Donald Trump will adopt a more presidential campaign style does not signal a retreat from core policies such as his pledge to build a wall on the Mexican border, his top adviser says.
Senior Trump aide Paul Manafort on Sunday dismissed rival Republican candidate Ted Cruz's accusation that the real estate mogul had lied about his policies on immigration to "fool gullible voters."
The tussle over Trump's style and substance preceded Tuesday's Republican and Democratic nominating contests in Pennsylvania and four other Northeastern US states: the next chapter in 2016's drawn-out selection of the candidates for November's presidential election.
Cruz seized on Manafort's comments at a closed-door meeting of top Republican officials in Florida on Thursday that Trump, 69, would temper the image he has projected so far, saying the "part that he's been playing is now evolving."
"I never said Trump wasn't going to build a wall. I never said Trump was going to change any of his positions," Manafort said on Fox News Sunday.
The adviser said Cruz, a 45-year-old US senator from Texas who is Trump's closest rival, was trying to distract voters from his own difficult path to the nomination. Ohio Governor John Kasich, 63, is also vying to be the Republican candidate.
But, despite Manafort's promise of a more restrained tone, Trump has continued to employ insulting nicknames at rallies, on Saturday referring to Cruz as "Lyin' Ted."
The billionaire New Yorker has alarmed some senior party figures with unflattering descriptions of Mexicans, a pledge to immediately deport millions of illegal immigrants and a proposed temporary ban on Muslims entering the country, among other things.
The rhetoric has drawn protesters to Trump rallies, sometimes culminating in scuffles. On Sunday, Connecticut State Police arrested a 20-year-old man, saying he had posted a threat on Twitter to bomb an upcoming Trump rally.
On Tuesday - one week after Trump's crushing win in New York's primary election - Pennsylvania, Maryland, Delaware, Connecticut and Rhode Island will hold their primaries.
Democratic front-runner Hillary Clinton's campaign says the former secretary of state now has an essentially insurmountable lead over rival Bernie Sanders. The 74-year-old US senator from Vermont has no plans to drop out of the race, according to his staff, who are counting on defying pollsters with some surprise wins on Tuesday.