On Friday, Reuters reported that Twitter had deleted more than 10,000 bot accounts that were tweeting messages aimed to keep people from voting in the midterms next week. The accounts were masquerading as Democrats, and Twitter reportedly removed the bots in late September and early October after someone from the party contacted the company.

While 10,000 is a tiny number compared to other account suspension efforts from the social network this year—Twitter purged more than 70 million fake accounts in May and June alone—the latest removal showed just how daunting the challenge of scrubbing disinformation from the sprawling and often anonymous social network is. No matter how many are swatted away, a new army of trolls seems to inevitably return.

The 10,000 fake accounts were first spotted by the Democratic Congressional Campaign Committee, a group that works to get Democrats elected to the U.S. House of Representatives. That group has been working to spot misinformation that may circulate about Democratic candidates. The effort reportedly started in response to false and misleading information that spread about Democratic candidate Hillary Clinton in advance of the 2016 election.* In February, special counsel Robert Mueller indicted a number of Russians with conspiracy to defraud the United States in connection with the country’s alleged social media propaganda campaign to influence the 2016 race.

According to Reuters:

The [latest] Tweets included ones that discouraged Democratic men from voting, saying that would drown out the voice of women, according to two of the sources familiar with the flagging operation.

The accounts appear to have originated in the U.S., CNET reports. As Election Day approaches, it’s safe to expect more of this kind of activity. What’s less clear is the impact these disinformation campaigns have on electoral outcomes—the question of whether Russia’s efforts in 2016 tilted the presidential election to Donald Trump is still hotly debated, with the intelligence community refusing to weigh in one way or the other and the president flatly denying it had an impact. Claims about things like long lines and broken machines are likely to spread on social media as well, come Tuesday. Those are the type of messages that can discourage turnout—and that are hard to fact-check before they go viral.

If you see what you believe to be disinformation or posts intended to confuse people about the midterm elections on social media, please email april.glaser@slate.com

Correction, Nov. 2, 2018: This post originally misspelled Hillary Clinton’s first name.