(Reuters) - When conservative meme-maker Carpe Donktum got an invitation to a White House summit, he thought the email might be spam.

FILE PHOTO: U.S. President Donald Trump speaks about his administration's environmental policy during a speech in the East Room of the White House in Washington, U.S., July 8, 2019. REUTERS/Carlos Barria/File Photo

“I asked around because I wasn’t sure if it was a mass marketing thing,” said the stay-at-home dad who lives in Kansas City, Missouri, declining to give his real name for fear of harassment against his family.

He churns out social media content that has been shared by U.S. President Donald Trump and last year won a $10,000 meme contest run by Infowars, the website founded by conspiracy theorist Alex Jones. His alias is made-up Latin for “seize the donkey,” referring to the Democratic Party symbol.

On Thursday, he will join other pro-Trump online personalities for what the White House billed as a gathering of “digital leaders” where invitees expect to discuss alleged censorship by the tech giants.

Facebook Inc FB.O said it had not been invited while Twitter Inc TWTR.N and Reddit declined to comment. Alphabet Inc's GOOGL.O Google did not respond to requests for comment.

Carpe Donktum, who was recently suspended by Twitter for eight days over a video depicting Trump as a cowboy attacking CNN journalist Jim Acosta, said the face-to-face event could unite online conservatives.

The meme-maker was not the only one surprised at his call-up. John Matze, the libertarian CEO of Parler, a Twitter alternative used by Trump supporters, said he had tracked the IP address to ensure his invitation was real.

Invitees said they had received little information about the event but in a statement to Reuters, the White House positioned it as follow-up to an online survey launched by the administration in May for people to report “suspected political bias” on social media.

“After receiving thousands of responses, the president wants to engage directly with these digital leaders in a discussion on the power of social media,” said White House spokesman Judd Deere.

Some who will be attending saw it as more of a political gesture than a policy discussion.

“There’s been nothing that’s given me any reason to believe that I should be preparing a Powerpoint or a white paper,” said Ron Coleman, an attorney focused on free speech and the internet.

The White House spokesman said Trump would deliver remarks and that about 130 people would attend, without providing a guest list.

A White House official confirmed Wednesday that Ben Garrison, a cartoonist who drew a 2017 cartoon attacking then national security adviser H.R. McMaster that the Anti-Defamation League labeled “blatantly anti-Semitic,” had been disinvited.

Senate Democratic Leader Chuck Schumer slammed the White House for issuing the original invitation.

“A social media summit designed to give support to the most radical viewpoints on social media should never have been planned by the White House in the first place,” he said on the Senate floor.

Far-right activist Laura Loomer, one of Coleman’s clients, voiced frustration on Parler because she was not invited.

“The weirdest part about it is the White House knows who I am … yet I am intentionally kept out,” said Loomer, who is currently suing Twitter over her ban from the site for hateful conduct after criticizing U.S. Representative Ilhan Omar and her Muslim faith.

Those who made the list include Trump pundit Bill Mitchell, Ryan Fournier, the 23-year-old chairman of grassroots group Students for Trump, and Charlie Kirk, the founder of conservative student group Turning Point USA.

Also going are James O’Keefe, CEO of conservative activist group Project Veritas, known for its sting operations and publishing of leaked tech company documents, and Prager University, a conservative non-profit that has sued Google and YouTube alleging censorship of its videos.

Trump made social media a key part of his 2016 presidential campaign but he and other Republicans have long claimed that online platforms employ tactics to silence their voices, allegations that major social media companies have denied.

When Trump, who has more than 61 million Twitter followers, met with the site’s chief executive, Jack Dorsey, in April, he spent significant time asking why he had lost followers, a source told Reuters.