(Bloomberg) -- An online feud between two of the top Democratic presidential candidates took an odd turn Wednesday morning when defenders of Senator Elizabeth Warren helped promote a hashtag ostensibly attacking her. It was an instructive moment in the mechanics of online political discourse as passions around the 2020 election season rise.The situation began Tuesday at the Democratic presidential debate. Some of the most dramatic moments of the night were exchanges between Warren and Senator Bernie Sanders, in the wake of reports that he had told Warren a woman could not be elected president, which she confirmed and he denied.After the debate, a video circulated appearing to show Warren refusing to shake Sanders' hand, followed by a sharp exchange ending with Sanders turning and walking away abruptly. Warren said to Sanders, 'I think you called me a liar on national TV.'On Wednesday morning, the hashtag NeverWarren appeared at the top of Twitter's trending topics. As of late Wednesday afternoon it had been mentioned more than 80,000 times, according to Ben Nimmo, director of investigations for social media monitoring company Graphika. 'It looks like it started off among some long-standing Sanders supporters,' he wrote in an email, 'but the most striking thing is that all the most-retweeted posts are of people criticizing the hashtag and the mentality behind it, and/or calling for unity.'The hashtag fit into a long-running narrative about Sanders supporters, who some Democrats criticized in 2016 for being insufficiently supportive of Hillary Clinton in the general election. Even before the debate Tuesday a faction of his fans had signaled they might not vote for any other Democratic nominee. This faction was clearly somewhat responsible for pushing the anti-Warren hashtags Wednesday.The Sanders campaign itself didn't seem to be involved. His spokeswoman, Briahna Gray, repeatedly Tweeted the hashtag WomenForBernie, but did not use the NeverWarren hashtag. Some pro-Sanders activists discouraged others from using it.A significant amount of the NeverWarren activity actually came from those trying to rebut its message. NBC News reporter Ben Collins used a disinformation identification tool to determine that the three most popular tweets using the hashtag were all denouncing it. Mehdi Hasan, a columnist at the Intercept, tweeted, 'Yep, let's be clear: if you're tweeting in support of this ludicrous NeverWarren hashtag, you're not only dumb but you're also telling the world that you're ok with kids in cages and bans on Muslims.' That message has received more than 1,700 retweets.Britt Julious, a Chicago Tribune columnist, posted a tweet attacking the hashtag (while still deploying it). She received more than 1,200 retweets.'I thought it was odd that it was trending when I woke up this morning. When I looked through the hashtag, I saw that it was a lot of Warren supporters who seemed upset that it was trending,' Julious wrote in an email, saying she remembered a similar dynamic during the 2016 campaign. 'Twitter tends to have that echo effect. Like one person will say something weird and then someone else finds it, replies back trying to shoot it down, and the pileup begins.'There has been evidence of significant manipulation of trending topics for years, including numerous media reports exposing coordinated activity pursuing commercial and political ends.Nor is this the first example in the 2020 Democratic primary. Late last year, a comedy troupe managed to get the hashtag DropOutBloomberg onto the list of trending topics, after members pretended the Michael Bloomberg presidential campaign had fired an intern for tweeting a bizarre (and fictional) Bloomberg campaign staff dance video. Some of the people tweeting the hashtag were clearly in on the joke. Others didn't seem to be. (Bloomberg is the founder and majority owner of Bloomberg LP, the parent company of Bloomberg News.)A major reason things like this happen is that Twitter has automated its trending topics. The company's algorithms look for hashtags that are included in large numbers of tweets, not necessarily the underlying message of the tweets. A Twitter spokeswoman wrote in an email that 'people can choose to Tweet with a hashtag they might disagree with, and our Trends product neutrally represents their behavior in the form of a trending topic.'Alex Stamos, a disinformation expert and former Facebook executive, said many Twitter users don't realize that by quote tweeting a message that they disagree with, they're only fueling the underlying hashtag. 'Some of these hashtags, it's like a ten-to-one ratio of people criticizing the hashtag do to people pushing it,' Stamos said in a phone interview.Activity on Twitter can inspire news coverage that fails to interpret the context. The Hill and the Daily Wire wrote about the NeverWarren hashtag. CNN's Chris Cillizza also mentioned it without explaining that much of the engagement came from Warren's defenders.Stamos cautioned that Twitter isn't representative of actual public sentiment and that some of the accounts tweeting about Warren have racked up thousands of tweets within a few days of creation, a suspicious sign. 'There's empirical evidence over and over again that Twitter does not reflect political reality in the United States.'Meanwhile, pro-Sanders accounts flooded Warren's Twitter mentions with images and emojis of snakes--an icon typically lobbed at women accused of being dishonest.In a tweet, Stamos encouraged users to change their behavior to avoid accidentally promoting that which they oppose. He wrote, '1) Don't use a hashtag to criticize that hashtag. 2) Stop quote-tweeting small-follower accounts as criticism. 3) Don't believe that the population of 'people' on Twitter is reflective of anything, including 'candidate X's followers.''(Updates third paragraph with Warren's post-debate remarks)To contact the reporter on this story: Eric Newcomer in San Francisco at email@example.comTo contact the editors responsible for this story: Mark Milian at firstname.lastname@example.org, Joshua BrusteinFor more articles like this, please visit us at bloomberg.comSubscribe now to stay ahead with the most trusted business news source.2020 Bloomberg L.P. Click here to read full news..