It is unclear if Google and Twitter will follow suit.
Facebook to drop on-site support for political campaigns
Facebook said on Thursday that it would no longer dispatch employees to the offices of political campaigns to offer support ahead of elections, as it did with President Donald Trump in the 2016 race.
The company and other major online ad sellers including Google and Twitter have long offered free dedicated assistance to strengthen relationships with top advertisers such as presidential campaigns.
Brad Parscale, who was Trump's online ads chief in 2016, last year called onsite "embeds" from Facebook crucial to the candidate's victory. Facebook has said that Democratic challenger Hillary Clinton was offered identical help, but she accepted a different level than Trump.
Google and Twitter did not immediately respond to requests to comment on whether they also would pull back support.
Facebook said it could offer assistance to more candidates globally by focusing on offering support through an online portal instead of in person. It said that political organisations still would be able to contact employees to receive basic training on using Facebook or for assistance on getting ads approved.
Facebook, Twitter, and Google served as "quasi-digital consultants" to US election campaigns in 2016, researchers from the University of North Carolina at Chapel Hill and University of Utah found in a paper published a year ago.
EU Justice Commissioner Vera Jourova has warned tech giants over rules. EPA
Facebook and Twitter face sanctions unless they comply with European consumer rules by the end of the year, the EU said as its regulators continue to their crackdown on US social media giants over privacy concerns.
Online platforms have come under fire in Europe because of their dominance and anti-competitive business practices, resulting in hefty fines handed down to some companies.
Seven months after being told to bring their user terms in line with EU regulations, both Facebook and Twitter have yet to fully address all the issues, the European Commission said on Thursday.
In contrast, Airbnb made the necessary changes after being told to do so three months ago, European Justice Commissioner Vera Jourova said.
"If we don't see progress, the sanctions will come," she said. "This is quite clear. We cannot negotiate for ever, we need to see the results."
Twitter should also make the necessary changes by year-end, a Commission spokesman said.
The companies helped campaigns navigate their services' ad systems and "actively" shaped campaign communication by suggesting what types of messages to direct to whom, the researchers stated.
Facebook's involvement with Trump's campaign drew scrutiny from US lawmakers after the company found its user data had separately been misused by political data firm Cambridge Analytica, which consulted for the Trump campaign.
In written testimony to US lawmakers in June, Facebook said its employees had not spotted any misuse "in the course of their interactions with Cambridge Analytica" during the election.