U.S. Republican presidential candidate Donald Trump on Tuesday detailed $5.6 million in contributions he raised for military veterans, and sharply criticized the news media for questioning him for months about what happened to the money.

At a combative news conference at Trump Tower in Manhattan, the billionaire accused the media of failing to give him credit for raising the funds at an event in January in Iowa.

Trump said the money was benefiting 41 groups. He was withering in his criticism.

"The press should be ashamed of themselves," Trump told reporters gathered before him. "You make me look very bad. I’ve never received such bad publicity for doing a good job."

He called an ABC News reporter at the event, Tom Llamas, "sleazy" and said Jim Acosta of CNN was "a real beauty."

Trump's criticism flew in the face of the hopes of some Republican leaders who want him to tone down his rhetoric and become more magnanimous now that he has sealed the Republican presidential nomination for the Nov. 8 election.

Trump, whose bellicose rhetoric has been a trademark of an insurgent candidacy that has upended the Republican Party, has shown no signs of doing so.

Last week, he attacked some of his former rivals for the Republican presidential nomination and a popular Latina Republican governor, Susana Martinez of New Mexico.

Trump said the coverage of his veterans group donations had been close to libelous. Asked whether he would keep his adversarial stance with reporters if elected president, Trump said: "Yeah, it's going to be like this."

The New York real estate mogul also bristled at the possibility that Republicans opposed to him might run a third-party candidate as an alternative to him or the expected Democratic nominee, Hillary Clinton.

He said a leader of that effort, Bill Kristol, editor of the Weekly Standard magazine, "looks like such a fool."

"Let me tell you these people are losers," said Trump, adding that a third-party candidacy would guarantee Clinton wins the White House and deny Republicans the chance to put conservatives on the Supreme Court.

"What you’re going to do is lose the election for the Republicans and therefore you lose the Supreme Court," he said.

Trump read out a list of veterans' organizations that had received money from the January event, which he attended instead of participating in a Fox News-sponsored candidates debate. He said the total of money raised for veterans could climb higher as more comes in.

He turned the microphone over briefly to Al Baldasaro, a Trump supporter and a veteran from New Hampshire, who also skewered the news media, saying reporters should "get your head out of your butt and focus on the real issues."