President Donald Trump doubled down on threats against Facebook, Twitter and Google Tuesday afternoon, saying the social platforms are "treading on very, very troubled territory and they have to be careful." "Google has really taken advantage of a lot of people and I think that's a very serious thing and it's a very serious charge," Trump told reporters after a meeting with the president of FIFA. "They better be careful because they can't do that to people." A Twitter spokesperson, when asked to respond to Trump's comments, pointed to previous statements and congressional testimony denying any form of conservative bias on the platform. A spokesperson for Facebook did not immediately return request for comment. Trump earlier Tuesday accused Google of altering search results to prioritize negative coverage and left-leaning outlets and warned that the issue "will be addressed."

Trump said in a tweet that the tech giant's search engine had "rigged" news story results to show mostly "bad" stories about him and other conservatives. "Google search results for 'Trump News' shows only the viewing/reporting of Fake New Media," the president said. "In other words, they have it RIGGED, for me & others, so that almost all stories & news is BAD. Fake CNN is prominent. Republican/Conservative & Fair Media is shut out."

Trump added: "Illegal? 96% of … results on 'Trump News' are from National Left-Wing Media, very dangerous. Google & others are suppressing voices of Conservatives and hiding information and news that is good. They are controlling what we can & cannot see. This is a very serious situation-will be addressed!" Around 11 a.m. ET, Trump deleted the original tweets and reposted practically identical language. "When users type queries into the Google Search bar, our goal is to make sure they receive the most relevant answers in a matter of seconds," a Google spokesperson said in a statement Tuesday. "Search is not used to set a political agenda and we don't bias our results toward any political ideology. Every year, we issue hundreds of improvements to our algorithms to ensure they surface high-quality content in response to users' queries. We continually work to improve Google Search and we never rank search results to manipulate political sentiment." Trump also praised the performance of the Nasdaq Composite index, which climbed above 8,000 points for the first time ever Monday. Tweet Google's parent company Alphabet is a key driver of the Nasdaq's performance. The firm's shares were under pressure following Trump's comments, down around 0.5 percent. Later Tuesday, Larry Kudlow, Trump's economic advisor, told Bloomberg that the White House is "looking into" whether Google suppresses positive articles about the president. Kudlow did not provide details on how the White House was looking into the matter. Tweet Some reports have suggested the president was referring to an unscientific report by conservative news website PJ Media, which claimed that 96 percent of Google search results for the word "Trump" showed left-leaning publications. The report places outlets including CNN, The Washington Post and The Guardian on the left of the political spectrum, while placing the likes of Fox News, the New York Post and the Daily Mail on the right.

Big tech to face Congress

Trump's comments couldn't be more timely. Next week, Google, Facebook and Twitter representatives will testify before Congress, discussing censorship and election meddling. The hearings mark the second time representatives from all the companies will be on Capitol Hill to address concerns of election interference. For Facebook, it will be the third, following CEO Mark Zuckerberg's grilling earlier this year over the Cambridge Analytica scandal. Twitter Chief Executive Jack Dorsey and Facebook Chief Operating Officer Sheryl Sandberg are among those confirmed to be attending the hearings. Facebook and Twitter have suspended hundreds of accounts ahead of the November midterm elections to avoid interference from foreign actors. Facebook last week said it had removed 652 pages, groups and accounts linked to Iran over "coordinated inauthentic behavior" targeting people in the U.S., the U.K., Latin America and the Middle East. As of Tuesday, Twitter has removed 770 accounts over "coordinated manipulation" ahead of the midterms. Trump's comments as a whole appear to represent a broader view among conservative circles that digital platforms are censoring them. The president recently accused Twitter of "shadow banning" — allegedly limiting search results — for prominent Republicans, and called the practice "discriminatory and illegal." Twitter has denied the claims. And earlier this month, multiple tech companies, including Apple, Facebook, Google's YouTube, Pinterest and Spotify, clamped down on content by the right-wing conspiracy theorist Alex Jones, removing podcasts, pages and other content. Tech companies said they removed Jones for violating policies related to hate speech and harassment. "Apple does not tolerate hate speech, and we have clear guidelines that creators and developers must follow to ensure we provide a safe environment for all of our users," Apple said at the time. Some right-wing commentators have criticized the mass takedown of Jones' content, saying it amounted to censorship. —CNBC's Sara Salinas contributed to this report.

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