While top executives from Alphabet, Meta and Microsoft headed to Capitol Hill on Wednesday for a hearing on election threats, Elon Musk’s X did not participate, according the office of the Senate Intelligence Committee chair.

A representative for Sen. Mark R. Warner, the Democratic chair, said in an emailed statement that X “declined to send an appropriate witness.” No further details were provided.

A spokesperson for X told CNBC that the company’s invited witness was Nick Pickles, who had been the head of global affairs but “resigned on September 6.” Warner’s office said X declined to send a replacement after Pickles’ departure.

Alphabet, the parent company of Google, is being represented by Kent Walker, the president and chief legal officer, while Meta’s head of global affairs, Nick Clegg, represents the social networking company. Microsoft President Brad Smith is representing the software giant.

The hearing, which is being led by Warner, of Virginia, and committee Vice Chairman Marco Rubio, R-Fla., is centered around lawmakers’ concerns over foreign entities that are attempting to influence the outcome of the presidential elections in November using the biggest tech platforms.

Alphabet and Microsoft recently published research into the efforts by Iranian and Russian hacking groups to influence or attack officials linked to President Joe Biden and former President Donald Trump. The hackers have used various tactics including spear phishing.

The Biden administration said on Sept. 4 that it’s targeting Russian government-sponsored attempts to affect U.S. public opinion.

“We will be relentlessly aggressive in countering and disrupting attempts by Russia, Iran, as well as China or any other foreign malign actor” attempting to “interfere in elections and undermine our members,” Attorney General Merrick Garland said in a statement at the time.

X’s absence from the Wednesday hearing follows a streak of divisive posts by Musk, the world’s richest person, on the app, formerly known as Twitter, which he acquired in 2022. Musk has nearly 200 million listed followers.

After a second apparent assassination attempt against Republican former Trump on Sunday, Musk shared and then deleted a post in which he wondered why “no one” was making assassination threats against Biden and Vice President Kamala Harris, the Democratic nominee. Biden and Harris have both received assassination threats while in office.

European news agencies reported this week that Musk has previously shared content on X that had been created by the Social Design Agency, which led a propaganda campaign at the Kremlin’s direction, according to the U.S. Department of the Treasury’s Office of Foreign Assets Control.

On Wednesday, Musk shared a false story on X that claimed explosives were found in a car near a planned Trump rally in Long Island, New York. According to a statement from Nassau County police, a civilian near the site of the rally had falsely reported explosives being found.

In the early stages of the meeting Wednesday afternoon, Warner said “it’s a shame” that no one from X appeared. He said that, prior to Musk’s takeover, the company was a “collaborator.”

“Under X, they are absent and some of the most egregious activity has taken place” on the platform, Warner said.

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