Donald Trump is set to welcome a series of far-right online figures to the White House for a social media summit in which none of the major tech companies have received an invite.

Among the guests invited was an artist who once published an antisemitic George Soros cartoon and conservative activist accused of trying to trick a major US newspaper into publishing a fake news story.

It comes just a week after Mr Trump hosted a meeting in the Oval Office with two Trump-supporting meme makers whose content has been promoted by both the US president and his allies.

The summit on Thursday, which will also attract Republican lawmakers and strategists, is likely to act as a stage for Mr Trump to further promote an unfounded conspiracy theory that social media companies are suppressing conservative voices.

It follows months of attacks on Twitter and Facebook by Mr Trump, who has suggested the companies may be acting illegally and should be sued by US regulators.

Trump 2020 launch: Fascist Proud Boys, baby blimps and Uncle Sam Show all 30 1 /30 Trump 2020 launch: Fascist Proud Boys, baby blimps and Uncle Sam Trump 2020 launch: Fascist Proud Boys, baby blimps and Uncle Sam Members of the Proud Boys, a fascist group, jeer at anti-Trump protesters outside of the president's 2020 campaign launch in Orlando, Florida Getty Trump 2020 launch: Fascist Proud Boys, baby blimps and Uncle Sam A supporter dressed as Uncle Sam poses at Uncle Sam Reuters Trump 2020 launch: Fascist Proud Boys, baby blimps and Uncle Sam A baby blimp rears its head amidst a group of anti-Trump protesters outside the president't campaign launch in Orlando, Florida Getty Trump 2020 launch: Fascist Proud Boys, baby blimps and Uncle Sam President Trump addresses supporters at the launch event of his 2020 election campaign in Orlando, Florida Reuters Trump 2020 launch: Fascist Proud Boys, baby blimps and Uncle Sam Proud Boys have adopted Fred Perry polo shirts as their uniform and 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Conservative organisations expected to participate in the White House meeting include Turning Point USA, PragerU - short for Prager University - which puts out short videos with a conservative perspective on politics or economics, and the right-wing Washington think tank Heritage Foundation.

But it was also initially set to include Ben Garrison, a cartoonist who in 2017 published an image depicting former US national security officials as puppets controlled by Jewish philanthropist Mr Soros, who in turn is puppeteered by an arm with “Rothschilds” written across the sleeve.

Politico reported the White House rescinded the invitation late on Tuesday night after it was asked questions about the cartoon.

The image was condemned as “blatantly antisemitic” by the Anti-Defamation League, which said said it had been commissioned by Pizzagate conspiracy theorist Mike Cernovich.

Another attendee, James O’Keefe, runs an organisation called Project Veritas which attempts to damage figures and institutions it perceives to be anti-conservative.

It infamously attempted last year to deceive Washington Post reporters into publishing false allegations that a woman had been impregnated by Republican politician Roy Moore, in an apparent effort to discredit the newspaper’s coverage of him.

According to NBC News, they will also be joined by GOP activist Ali Alexander, whose fake Kamala Harris birther conspiracy was promoted by Donald Trump Jr, and QAnon conspiracy theorist Bill Mitchell.

White House spokesman Judd Deere said the White House conference on Thursday would bring together "digital leaders for a robust conversation on the opportunities and challenges of today's online environment".

Two right-wing meme creators, who use the handles @mad_liberals and @CarpeDonktum, have already attended a 20-minute meeting with the president in the White House. Both said they had received invitations to Thursday’s summit.

During the 3 July meeting, Mr Trump asked of @CarpeDonktum, “Where is the genius? I want to meet the genius”, as he walked into the Oval Office, according to @mad_liberals. Both spoke to the Washington Post on condition their real names were excluded.

@CarpeDonktum has been behind a handful of comedically doctored videos which were subsequently tweeted by Mr Trump, including one in which former vice-president Joe Biden sneaks up on himself during a video in which he addresses sexual misconduct allegations.

@CarpeDonktum has complained of social media bias after Twitter temporarily banned his account for posting a video depicting Mr Trump repeatedly slapping CNN reporter Jim Acosta in the face.

Mr Trump and some supporters have long accused Silicon Valley companies of being biased against them. Accusations commonly levelled against the platforms include anti-religious bias, a tilt against those opposed to abortion and censorship of conservative political views. While some company executives may lean liberal, they have long asserted 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 Michael Beckerman said in a statement. He added 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."

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

Mr Trump has played to conservative concerns about bias on other issues. In March, he signed an executive order requiring US colleges to protect free speech on their campuses or risk losing federal research funding.

The order cheered those who said universities were attempting to silence some conservative students and speakers. But critics called the order unnecessary.

The president himself was dealt a setback on Tuesday in his legal battle against Twitter, his favoured means of communicating. A federal appeals court in New York City ruled the president cannot ban critics from his Twitter account, saying the First Amendment calls for more speech, rather than less, on matters of public concern.

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Mr 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".

Thursday's conference raised questions about whether Mr 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 Mr 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.

A growing number of lawmakers and some Democratic presidential candidates are talking about tighter regulation of a customarily freewheeling industry or even breaking up the big companies.

But if Mr Trump is looking for the participating conservative groups to support government action to bring the companies in line on perceived social media bias, he may be disappointed.

Rob Bluey, vice president for communications at the Heritage Foundation, said that "if the government were to get involved, it would lead to more problems". He said market pressures can produce positive changes.

Turning Point USA keeps a list of college professors who it says discriminate against students with conservative views.

"I think there will be some form of equilibrium" between the social media platforms and Americans who hold right-of-centre views, Charlie Kirk, the group's executive director, said on Tuesday. "Hopefully these companies can self-correct."

"Voters will be constructing their choices for 2020" based largely on information from social media, Mr Kirk added.

Mr Trump said last week on Fox News that Google, Facebook and Twitter "are fighting me hard right now, which is incredible because I think the Democrats want to shut them up and, frankly, so do a lot of the Republicans want to shut them up".

Asked whether tech companies may be acting illegally and whether the Justice Department should determine that, Mr Trump replied, "Well, they could be and I don't want to even say whether or not they're doing something, but I will tell you, there are a lot of people that want us ... to take action against Facebook and against Twitter and, frankly, against Amazon."

Mr Trump told Fox Business Network's Maria Bartiromo last month he did not know if tech comapanies were doing anything illegal, but added, "I tell you what, they should be sued because of what's happening with the bias".