The Post’s Margaret Sullivan explores what might have led Donald Trump to revoke the newspaper’s media credentials. (Peter Stevenson/The Washington Post)

A day after Donald Trump revoked The Washington Post’s credentials to cover his campaign last week, one of the newspaper’s reporters walked into his rally in Greensboro, N.C., and began reporting on it. The only difference was that the reporter, Jenna Johnson, entered on a general-admission ticket, not a press pass. She sat in the audience instead of the designated media “pen” and later filed a story.

So much for being barred from covering Donald Trump.

Johnson’s experience says much about the practical impact of Trump’s efforts to banish news organizations whose reporting has displeased him. For the most part, Trump’s sanctions against the press haven’t made much difference. Although the dozen or so news outlets that have been blacklisted certainly object to being shut out, they say the restrictions are largely symbolic, an attack on traditional norms, and don’t deter reporting on the presumptive Republican nominee.

“Access has never been central to our journalism, and we think the best reporting done on Trump, by us and others, is from the outside,” said Ben Smith, the editor of Buzzfeed, which hasn’t been accredited by Trump since he announced his candidacy a year ago.

Getting on Trump’s blacklist does present a few logistical hassles. Reporters from affected organizations have to wait longer to enter Trump’s events; they can’t attend or ask questions at his news conferences; and they tend not to get interviews with Trump or his staff.

Trump, seen here in New York last month, has made a habit of yanking press credentials from media outlets that displease him. (Carlo Allegri/Reuters)

But for every restriction, there’s a workaround. The Des Moines Register, banned by Trump since last summer, gets audio and video footage of the candidate’s events and copies of his press statements from friendly third parties in the news media, said Annah Backstrom, who oversees the paper’s political reporting. The paper’s reporters have covered his events the same way The Post did: by securing a publicly available ticket. If all else fails, a verboten news organization can hire a freelancer to cover for it.

It’s not entirely clear how Trump decides who or what organizations to ban. The most obvious element is a persistent pattern of stories he doesn’t like — although one strike is sometimes enough, too.

The Huffington Post, for example, went into Trump’s penalty box early on by consigning coverage of him to its entertainment section. (It has since changed its mind but is still banned.) The Washington Post got the hook a week ago for a headline suggesting that he had tied President Obama to the nightclub massacre in Orlando — even though the Wall Street Journal ran a similar headline on its story without incurring his wrath. Both the Des Moines Register and the New Hampshire Union Leader lost access not for news stories but for anti-Trump editorial columns.

Trump has banned only two TV networks — the Spanish-language broadcaster Univision and the Fusion channel, which is part-owned by Univision — and only briefly at that. This suggests that the onetime reality-TV star has been careful not to alienate TV broadcasters, thus preserving his access to the medium he likes best, although he has frequently disparaged TV reporters on Twitter and at news conferences. The two networks were frozen out after Univision dropped its telecast of the Trump-owned Miss Universe pageant following Trump’s remarks that Mexican immigrants are “rapists.” (Trump sued Univision over the cancellation but dropped his lawsuit in February.)

Reporters banned by Trump get their credential requests turned down via a robo-email from the Trump campaign that says the following: “During the 2016 Presidential Primary race, the Donald J. Trump Campaign fully recognizes and respects all media but due to various venue sizes, media space, and safety, we must limit the number of credentialed media and give priority to our national and local outlets. We appreciate your understanding.”

Those still on the banned list have found that Trump’s restrictions are often arbitrarily enforced and vaguely defined. Reporters from some blacklisted outlets still receive news releases from his campaign; others don’t. A day after Trump sanctioned The Post, one of the paper’s reporters got a call back from Trump’s press handlers, suggesting the lines of communications are still open (the campaign has been responsive to other Post reporters in recent days, including Johnson). But others face a complete blackout. The campaign did not respond to several requests for comment for this article.

The Post doesn’t know yet whether Trump’s sanctions against the newspaper extend to the Republican convention next month or to the team of reporters who are producing a book about him. The Post’s book team has interviewed Trump many times, including two weeks ago, when he expressed enthusiasm for the project and invited the journalists back for more interviews. But Trump has also publicly trashed the book, telling Fox News at one point that the paper has been asking him “ridiculous questions” about his past.

The real objections to Trump’s actions from the press aren’t about the inconvenience; they’re about the seemingly undemocratic nature of his actions. Candidates of every party rarely like the coverage they get, but few have resorted to banning a reporter, let alone entire news organizations.

“When I was in Moscow, Vladimir Putin’s Kremlin gave me credentials to cover his reelection campaign to a second term even after several years of critical coverage of his crackdown on Russian media and rollback of democratic reforms,” said Susan Glasser, the editor of Politico, whose beat reporter was banned by Trump in March. “It is just astonishing that something like this is happening in the United States.”