There was a brief moment after Donald Trump’s election when it was conceivable to ask whether he would strive to be a “uniter” or a “divider.” The moment passed quickly as Trump made it clear that he does not intend to abandon the style of politics — insulting and divisive — that got him elected. His declaration last week that the news media are “the enemy of the American people” is but the latest reminder.

Trump’s theory of politics is that it’s OK to offend five voters if seven voters approve. Dividing the country is the name of the game. The object is to create a coalition of the resentful. Polarization is not only the consequence. It is the underlying purpose and philosophy.

In this strategy, the news media are tempting targets. There are so few of them — actually, I mean so few of “us” — that we are easily cast as scapegoats for assorted disappointments. Even in good times, we can be hard to like. No one elected us; our political and cultural values are skewed liberal; and we are often arrogant in our assumed role as guardians of American democracy, holding elected officials accountable and defending free speech.

It’s also well-known that our popularity has plummeted. The latest Gallup poll finds that only 32 percent of adults “trust the mass media,” down from 55 percent in 1999. In another Gallup poll, which asks slightly different questions, the media’s standing seems even lower. Only 20 percent expressed strong confidence in newspapers, 21 percent in TV news and 19 percent in Internet news.

Just why confidence has collapsed isn’t clear. In part, it may reflect a general loss of trust in institutions. In 2016, confidence in Congress was 9 percent; in 1998, it was 28 percent. The explosion of news sources on cable and the Internet has probably contributed. Many sources (MSNBC, Fox News) are openly ideological. The more choices people have, the more they may think poorly of the ones they don’t make.

Regardless of cause, the present media-White House brawls are hardly without precedent. As Sanford Ungar — an ex-Washington Post reporter and expert on free speech — has reminded us, the confrontations over the war in Vietnam in the 1960s and Watergate in the early 1970s seem every bit as bitter and contentious as today’s media wars. This history suggests that the slugfests won’t soon abate.

For the press, it’s a matter of honor and self-interest. If we don’t exist to bring truth to power, why do we exist? Trump is correct when he asserts that the media have an agenda. One part is simply to expose what the Trump administration is — or isn’t — doing. Someone has to protect sensible policies as well as democratic and Constitutional norms, all of which, many believe, are assaulted by Trump.

But beyond this lies a silent goal: the search for some impeachable offense. If found, this would clearly justify the media’s obsessive attention to the president’s every move and policy. But if not found, the press risks losing more of its credibility by conducting a political witch-hunt. Meanwhile, Trump is good for business. He increases readership, page views and cash flow.

Ironically, Trump is fortifying financially prominent adversaries. This is unlikely to change the president’s behavior. He seems to have three reasons for attacking the press. One is an effort to discredit media criticism, especially of Trump’s own falsehoods, exaggerations and misleading statements. After Trump’s recent press conference, The Washington Post’s fact checkers — Glenn Kessler and Michelle Ye Hee Lee — found 15 examples of falsehoods or dubious claims. If people don’t believe the press, findings like these will matter less, if at all.

The second reason is an effort to associate all opposition to him with despised media “elites,” so that their unpopularity rubs off on his other critics. But Trump’s final reason for attacking the press may be the most powerful. He seems to enjoy it. He likes denouncing journalists as dishonest scum of the earth. It’s invigorating. Trump can’t be a unifying figure when he’s having so much fun being Divider in Chief.

Robert Samuelson is a columnist with The Washington Post Writers Group.