Fake Democrat accounts have been urging Americans not to vote.
Twitter has deleted more than 10,000 automated accounts posting messages that discouraged people from voting in Tuesday's US midterms, many which wrongly appeared to be from Democrats.
It came after the party flagged the misleading tweets to the social media company.
"We took action on relevant accounts and activity on Twitter," a Twitter spokesman said in an email to Reuters.
The removals represent an early win for a fledgling effort by the Democratic Congressional Campaign Committee, or DCCC, a party group that supports Democrats running for the US House of Representatives.
The DCCC launched the effort this year in response to the party's inability to respond to millions of accounts on Twitter and other social media platforms that spread negative and false information about Democratic presidential candidate Hillary Clinton and other party candidates in 2016, three people familiar with the operation told Reuters.
The tweets reportedly included ones that discouraged Democratic men from voting, saying that would drown out the voice of women.
For months, Twitter has sought to eliminate automated and bogus accounts designed to manipulate the public conversation on the platform, in response to concerns over Russian interference in the 2016 election.
In October it said its number of active users fell by nine million in the previous quarter as a result of these efforts.
US President Donald Trump recently complained that Twitter was removing some of his followers.
Additional reporting: Nick Baker, AFP