Twitter continued to add new fact-checking labels to hundreds of tweets, even as the Trump administration issued an executive order to curtail the legal protections that shield social media companies from liability for the content posted on their platforms... Twitter on Tuesday had appended fact-checking labels for the first time to two of Mr. Trump’s tweets about mail-in ballots, rebutting their accuracy. In response, Mr. Trump accused Twitter of stifling speech and... signed an executive order to make it easier for federal regulators to argue that companies like Facebook, Google and Twitter were suppressing free speech when they suspended users or deleted posts.

... A Twitter spokeswoman said that the tweets modified on Wednesday contained “potentially misleading content” and that the fact-checking was consistent with the company’s approach this month... Jack Dorsey, Twitter’s chief executive, also said he would not back down from the fact-checking effort. “We’ll continue to point out incorrect or disputed information."

... Mr. Dorsey has doubled down on fact-checking tweets, but Mark Zuckerberg, Facebook’s chief executive, has distanced his social network from that effort. “I just believe strongly that Facebook shouldn’t be the arbiter of truth of everything that people say online,” Mr. Zuckerberg said.