Donald Trump 'promises to change image'
Donald Trump has promised to change his image, in a closed-door meeting with Republican party leaders.
The businessman, who leads the party's race to be presidential nominee, delivered his message via aides, the Associated Press news agency reports.
His rival Ted Cruz seized on the leaked remarks, saying: "He's telling us he's lying to us.'
Five states go to the polls on Tuesday to pick their presidential candidates in the Republican and Democratic races.
Mr Trump's success in primary elections so far has set off alarm bells among those in the party anxious that his tone and policies will turn off voters.
He has a clear lead in the number of delegates but may fall short of the 1,237 threshold required to win the nomination without a contested convention - where the nominee is chosen through negotiations among party figures.
In a recording of Thursday's meeting obtained by Associated Press, his senior aides told Republican leaders that he has been "projecting an image" so far and "the part that he's been playing is now evolving".
Can it work? Anthony Zurcher, BBC News, Washington
It seems the Great Trump Pivot is official campaign strategy and not just pundit speculation.
Thanks to a "private" campaign presentation to Republican insiders that was destined to be leaked almost instantly, we now know that the kinder, gentler Donald Trump on display on Tuesday night is the course the campaign has charted for the home stretch.
If he wants to win the Republican nomination and be competitive in a general election in November, Mr Trump will have to walk a fine line in the coming months.
His pivot to moderation will have to convince Republican delegates that it's not suicide to put him at the top of their ticket, then erase the massive negative favourability ratings the New Yorker has among the US electorate at large - all without alienating the angry, disenfranchised base that has rocketed him to the top of the Republican heap.
At this point, Trump Nation seems willing to stand by their man through thick and thin. But can Mr Trump repair an image that has been severely tarnished among the larger US population?
Such an achievement would be unprecedented in modern US politics. Donald Trump, however, has made a nearly year-long habit of turning political convention on its head.
In it, his newly hired senior aide, Paul Manafort, told the Republican National Committee members that Mr Trump has a campaigning personality and a private one.
"When he's out on the stage, when he's talking about the kinds of things he's talking about on the stump, he's projecting an image that's for that purpose," he said.
He knows he needs to moderate his personality, Mr Manafort told the meeting. "The negatives [unfavourable ratings in polls] will come down. The image is going to change."
His standing among female voters is particularly low, after a series of controversial remarks about women, abortion and rival Ted Cruz's wife.
"He's being candid. He's telling us he's lying to us,'' said Mr Cruz.
"You look at what his campaign manager says, is that this is just an act. This is just a show."
Analysts say Mr Trump's decisive win in the New York primary this week seemed to signal a new, softer side in his victory speech.
And he told a rally in Pennsylvania on Thursday: "At some point, I'm going to be so presidential that you people will be so bored."
On one of the key social issues currently engulfing the party, transgender rights, he took a stance out of step with his key rival Mr Cruz on Thursday, when he said transgender people should be allowed to use a toilet assigned to a gender of their choosing.
Mr Cruz criticised this as politically correct but former candidate Ben Carson praised Mr Trump for "trying to moderate".
Mr Trump has accused the RNC of conspiring against him and of rigging the way delegates are awarded in a way that is unfavourable to him.