The top executives of Facebook and Twitter were set to appear before US lawmakers for the second time in less than month for a fresh hearing on the hotly disputed role of social networks in US political debate.
Facebook's Mark Zuckerberg and Twitter's Jack Dorsey were scheduled to appear remotely at the hearing before the Senate Judiciary Committee.
Both executives were testifying "voluntarily," according to the panel.
Committee chair Senator Lindsey Graham called the session to address what he called "censorship and suppression of news articles" and the "handling of the 2020 election" by the platforms.
Graham said the panel would notably address the decision by both social platforms to limit circulation of New York Post articles which claimed to have exposed malfeasance by Democrat Joe Biden ahead of his election victory.
President Donald Trump and his allies have claimed the major social platforms have suppressed conservative voices, despite his own large following and prolific posting.
The session follows an October 28 hearing at a different Senate committee -- which included Zuckerberg, Dorsey and Google CEO Sundar Pichai -- on the legal immunity of online services for content posted by others on their platforms.
Some lawmakers last month complained that the platforms were becoming biased "arbiters" of content and unfairly suppressing conservative voices.
The large networks have been struggling with ways to filter out abusive content and misinformation while keeping their platforms open to all voices.