Politico editor-in-chief John Harris has spent nearly three-and-a-half decades in American political journalism, building a reputation as a fair and principled reporter and, perhaps more important, helping to create a media organization that wields significant influence in Washington while commanding the respect of both Democrats and Republicans.

So when Harris became a target of conservative criticism last week because of a tweet that the Republican National Committee Chairwoman Ronna McDaniel described as "offensive" and "an example of why distrust in the media is at an all-time high," it left a few of his staffers feeling disappointed and perplexed. Some current and former Politico staff members who spoke on the condition of anonymity so they could speak freely about their employer expressed confusion and disappointment about Harris’ tweet.

It also served as a reminder of the perils journalists face on Twitter, where there is a temptation to stray from reporting and share jokes and opinions. One errant observation, or an improperly worded thought, and journalists can find that they've inadvertently exposed their own biases to the world — and caused a firestorm in the process.

In Harris' case, it was a tweet on Wednesday that seemed to imply President Donald Trump was a white nationalist. In response to an NBC News article about a white nationalist who wanted to "take over the GOP,” Harris tweeted, “Thought that job had been filled.”

The criticism came quick: Former White House Ppess secretary Sean Spicer called it a "partisan attack," while GOP operative Arthur Schwartz said Republicans should not take calls from Harris or his reporters "until this guy is gone from Politico" — critiques that also happened within the Twittersphere.

Harris later tweeted that he had been misunderstood, and that he only meant to make "a quip" about NBC's headline.

"Sometimes wisecracks get lost in Twitter translation so appreciate the chance to clarify,” he tweeted.

A fair point @ArthurSchwartz , this could be interpreted as broad swipe rather than a quip about the headline on the NBC piece. Sometimes wisecracks get lost in Twitter translation so appreciate the chance to clarify. pic.twitter.com/wpsXiHUoPq — John F. Harris (@harrispolitico) October 17, 2018

A lot gets lost on Twitter, which makes one wonder why a journalist of Harris' caliber was quipping on Twitter in the first place. The platform provides many invaluable services: It's a news ticker, a chat room, a place to promote one's work. It can also provide instant gratification: the chance to command attention, earn followers, engage with political adversaries and build a professional profile.

There are thousands of journalists on Twitter, most of whom tend to stay well within the bounds of professional use. But the nature of Twitter itself makes particular examples of partisan behavior stand out, in turn opening news organizations to accusations of partisan bias. While that has been true since the social media platform was created more than a decade ago, the vulnerability seems especially acute in this combative and hyperpartisan political climate.

Back in July, New York Times Magazine writer Emily Bazelon tweeted her opposition to Brett Kavanaugh's Supreme Court nomination, writing that his appointment would "harm the democratic process & prevent a more equal society." Three months later, The Times said it had erred in letting her report on Kavanaugh because she was not a newsroom reporter — even though her report was, as The Times said, "straightforward" and "fact-based."

It’s not just new tweets that are landing journalists in the middle of partisan controversy. Numerous writers have had to answer for old tweets after they've taken jobs at major media institutions, leading many journalists to begin deleting their old aacounts.

Jim VandeHei, the co-founder and CEO of Axios, who was also a Politico co-founder, recently went so far as to suggest that journalists stop sharing anything on Twitter other than links to published reporting. He also implied that reporters' social media activity almost always betrayed a left-wing bias.

"News organizations should ban their reporters from doing anything on social media — especially Twitter — beyond sharing stories," VandeHei said in remarks to students at University of Wisconsin-Oshkosh over the weekend. "Snark, jokes and blatant opinion are showing your hand, and it always seems to be the left one. This makes it impossible to win back the skeptics."

VandeHei said that Axios' social media policy "prohibits the sharing of political views or derogatory snark online: 'Don’t say anything on the internet that you wouldn’t publish under your byline or say on TV.'"

While other news executives aren't nearly as extreme in their view of Twitter as VandeHei, many are wary of social media's potential to undermine their organization's reputation and credibility. Many editors also chafe when they see reporters who are expected to be fair and nonpartisan fire off a pithy bit of snark or opinion, or get mired in a zero-sum debate with their critics. And the more notable a journalist is, the more leeway they tend to have in sharing their opinions on Twitter without repercussions.

In recent years, many newsrooms have put policies in place regarding reporters' social media activity, but they aren't always effective. NBC News guidelines dictate that social media accounts are held to the same news standards, including “principles of fairness, accuracy, respect for copyright laws and privacy rights” as editorial content — and that this applies to personal and professional accounts.

Several journalists took issue with VandeHei’s proposal on Sunday, arguing that journalists shouldn’t conceal their true feelings from readers.

"This sort of policy says: Yes, we have opinions and attitudes and sensibilities, like any intelligent person, but we will *conceal them from you.* And therefore you should trust us more!" James Poniewozik, The New York Times' television critic, tweeted. "What idiot would believe that? In what other aspect of journalism do we believe that hiding information from the public serves the public?"

Of course not! So this sort of policy says: Yes, we have opinions and attitudes and sensibilities, like any intelligent person, but we will *conceal them from you.* And therefore you should trust us more! 3/ — James Poniewozik (@poniewozik) October 21, 2018

“It’s slightly amusing to see Jim VandeHei lecture social media companies when not so long ago he wrote a WSJ op ed about how Mark Zuckerberg should be president,” tweeted Max Tani, a media reporter at The Daily Beast.

The latest debate is just part of a larger, longstanding conversation about Twitter's effect on journalism generally. Columbia Journalism Review's Mathew Ingram recently cited a study that found journalists’ news judgment was negatively affected by a preoccupation with Twitter. Some journalists, including The New York Times' Maggie Haberman, have also taken time away from Twitter because of what Haberman described as a general "viciousness," "toxic partisan anger," and "intellectual dishonesty."

Both VandeHei and Harris are familiar with how severe the repercussions for opinionated tweets can be. In 2012, when they were running Politico together, the organization suspended and then fired a reporter because of remarks he had made on television and Twitter, including one remark suggesting that Republican presidential candidate Mitt Romney was only comfortable around white people.

In the memo announcing the journalist's suspension, Harris and VandeHei reminded staff that all journalists had a "clear and inflexible responsibility to cover politics fairly and free of partisan bias."