▶ Watch Video: Zuckerberg says no new political ads on Facebook the week before Election Day

Facebook will reject political ads that claim victory in the presidential election before the results are declared, according to a company spokesperson.

CEO Mark Zuckerberg announced earlier this month that Facebook will work with the Reuters news agency and the National Election Pool — a group of American news organizations including CBS News that distribute exit polling data — to vet election results. He said “if any candidate or campaign tries to declare victory before the results are in, we’ll add a label to their post educating that official results are not yet in.”

Andy Stone, a Facebook spokesperson, indicated on Wednesday that the company will now go further.

“Facebook will be rejecting political ads that claim victory before the results of the 2020 election have been declared,” Stone tweeted.

When contacted by CBS News, he declined to elaborate on the new policy.

The announcement represents an about-face for the company, which has for years said it would not fact-check political advertisements made by presidential candidates and other international leaders. But it comes as the social media site has started to acknowledge it risks being used to foment tumult around elections. 

Zuckerberg said in his post on September 3 that the company “strengthened our enforcement against militias, conspiracy networks like QAnon, and other groups that could be used to organize violence or civil unrest in the period after the elections.”

Facebook is also planning to bar campaigns from advertising in the week before the November 3 election — because the company says contested claims can sometimes take more than a few days to be investigated and blocked — and has said it is already seeking to remove posts with “clear misinformation” about the coronavirus pandemic and voting. 

The company is additionally flagging some posts that strike at the legitimacy of mail-in and other forms of legal voting, or the election results themselves.  

“We will attach an informational label to content that seeks to delegitimize the outcome of the election or discuss the legitimacy of voting methods, for example, by claiming that lawful methods of voting will lead to fraud. This label will provide basic authoritative information about the integrity of the election and voting methods,” Zuckerberg wrote in his September 3 Facebook post.

Stone’s tweet about the latest policy was posted hours before President Trump declined during a press conference to commit to a peaceful transfer of power should he lose the November 3 election to Democratic nominee Joe Biden. 

“Well, we’re going to have to see what happens,” Mr. Trump said when asked by a reporter about transferring power. He then questioned the legitimacy of mail-in ballots, and predicted he’d win.

“There won’t be a transfer, frankly — there’ll be a continuation,” Mr. Trump said.