WASHINGTON — President Donald Trump is lashing out at social media companies and the press ahead of his White House ”Social Media Summit” gathering of mostly conservative groups.

Trump tweeted Thursday morning against social media companies, the press and his Democratic rivals, while calling himself “so great looking and smart, a true Stable Genius!”

Trump says a “big subject’ of Thursday’s summit “will be the tremendous dishonesty, bias, discrimination and suppression practiced by certain” companies.

Google, Facebook and Twitter weren’t invited to the event, their representatives have confirmed.

Trump has an estimated 61 million followers on Twitter. He has accused Twitter of making it “very hard for people to join me” and “very much harder for me to get out the message.” He has suggested the companies may be acting illegally and should be sued by U.S. regulators.

Trump frequently lashes out at the press, and did so again Thursday, tweeting that, “Fake News is not as important, or as powerful, as Social Media” and predicting outlets “will quickly go out of business” when he leaves office. He asserted that “even Social Media would be driven out of business” if he loses in 2020.

The White House conference offers Trump a chance to play to his conservative base in the lead-up to the 2020 election.

Among the conservative organizations that are expected to participate in the White House meeting: Turning Point USA; PragerU, short for Prager University, which puts out short videos with a conservative perspective on politics or economics; and the Washington think tank Heritage Foundation.

Trump and some supporters have long accused Silicon Valley companies of being biased against them. Accusations commonly leveled against the platforms include anti-religious bias, a tilt against those opposed to abortion and censorship of conservative political views. But while some company executives may lean liberal, they have long asserted that their products are without political bias.

Representatives for Facebook, Google and Twitter declined to comment specifically on Thursday’s meeting. But the Internet Association, the industry’s major trade group representing Facebook, Google and dozens of other companies, said the internet “offers the most open and accessible form of communication available today.”

Its members’ platforms “don’t have a political ideology or political bias,” the group’s president and CEO Michael Beckerman said in a statement. He added that the companies “succeed and grow by building a broad user base regardless of party affiliation or political perspectives.”

Twitter spokeswoman Katie Rosborough, in a statement, said “We enforce the Twitter rules impartially for all users, regardless of their background or political affiliation. We are constantly working to improve our systems and will continue to be transparent in our efforts.”

Thursday’s conference raised questions about whether Trump would use the forum to signal tough actions ahead by his administration against the big companies in the areas of competition and privacy.

Big tech companies already are under closer scrutiny than ever by regulators and in Congress following a stream of scandals including Facebook’s lapses opening the personal data of millions of users to Trump’s 2016 campaign. A bipartisan push for new data privacy legislation has emerged in Congress. Regulators at the Justice Department and the Federal Trade Commission are pursuing antitrust investigations of Facebook, Google, Apple and Amazon. The House Judiciary Committee has opened a bipartisan probe of the tech giants’ market dominance.