WASHINGTON – Republican establishment leaders now falling in behind Donald Trump hope he will somehow become more “presidential” as their party’s nominee and, if elected, as the Oval Office occupant.

That dream accounts for the likes of such conservatives as Chris Christie, Newt Gingrich, Marco Rubio and even John McCain, who are holding to their early vow to support the eventual nominee at the GOP convention next month in Cleveland.

But Trump characteristically threw cold water on the notion of a new, more presidential Donald in his whining and mean-spirited New York news conference Tuesday. He defended his promised charitable contributions to veterans’ groups while intensifying his indictment of reporters questioning him on the scope and timing of them.

Having repeatedly declared earlier that he had given $6 million, Trump was pressed on where and when the money went, and why he was saying now his donations amounted to (only) $5.6 million. He complained that reporters “make me look very bad,” adding, “I have never received such bad publicity for doing such a good job.”

The press conference was the result of press searches into Trump’s claims to have made the donations. His pushback prompted a reporter to ask whether this contentious session “is what it’s going to be going to like” if he is elected president. Trump instantly replied: “Yes, it is.”

He went on to castigate individual reporters, calling ABC News reporter Tom Llamas “a sleaze,” and charging the press as a group of being unfair in questioning his previously unspecified list of charitable recipients. At one point, he said: “I didn’t want to have credit. What I got was worse than credit, because they were questioning me.”

What, though, was he expecting after months of stonewalling on the purported donations, which he was using to peddle himself as a prime champion of American vets? For someone who works overtime using the news media to advance his notoriety, he seems to think he should be immune from legitimate inquiry into his affairs as a would-be president.

In the end, the encounter may have been a draw politically: The reporters got the details they had been seeking; Trump laid down a basis for his endless lament that the American news media collectively are against him.

Beyond that, Trump’s bitter and at times personal attacking was a troubling example of his contempt for the investigative role of the press and his strategy to cast it as an adversary. His behavior also was an illustration of his skill in tapping into the public’s own suspicions and dislike of print and electronic journalism in all its forms.

This clash has always existed in American politics. Ambitious office-seekers delve in deceptions and exaggerations to advance their personal and political objectives. Reporters pursue a range of techniques to ascertain the truth, or at least the most attainable version of it, sometimes in questionable overreach.

The Donald Trump phenomenon has put a particularly heavy and important burden on the nation’s news media to assess the man’s qualifications and fitness for the presidency.

At the highest level, at stake are not television ratings or newspaper sales but the prospects of a stable, just and prospering society for all who strive within it.

Virtually within one generation, this country has found itself ensnarled in an electronic communications revolution, in which skilled manipulators of words and images like Trump can command mass audiences as never before.

Trump has already captured one of the two major U.S. political parties with an agenda based on wide public discontent and stirring racial and ethnic divisions.

He may seem among disbelievers to be almost a cartoon character, too outrageously pompous and self-important, too full of sophomoric bombast and ignorance to be taken seriously.

But the way he has capitalized on the weakness and lack of direction in the Republican Party to take it over requires that the news media vigorously meet their own responsibility to examine Trump’s claims and methods of achievement.

Being “presidential” in style is only the least of what is expected of an Oval Office aspirant. Honesty, wisdom and a level-headed temperament also are needed, all too evidently lacking in this dangerous pretender.

Editor’s note: Jules Witcover’s latest book is “The American Vice Presidency: From Irrelevance to Power,” published by Smithsonian Books. You can respond to this column at juleswitcover@comcast.net.