Billionaire Elon Musk is already floating major changes for Twitter — and faces major hurdles as he begins his first week as owner of the social media platform.

Twitter’s new owner fired the company’s board of directors and made himself the board’s sole member, according to a company filing Monday with the Securities and Exchange Commission.

He’s also testing the waters by asking users to pay for verification. A venture capitalist working with Musk tweeted a poll asking how much users would be willing to pay for the blue check mark that Twitter has historically used to verify higher-profile accounts so other users know it’s really them.

Musk, whose account is verified, replied, “Interesting.”

Critics have derided the mark, often granted to celebrities, politicians, business leaders and journalists, as an elite status symbol.

But Twitter also uses the blue check mark to verify activists and people who suddenly find themselves in the news, as well as little-known journalists at small publications around the globe, as an extra tool to curb misinformation coming from accounts that are impersonating people.

“The whole verification process is being revamped right now,” Musk tweeted Sunday in response to a user who asked for help getting verified.

On Friday, meanwhile, billionaire Saudi Prince Alwaleed bin Talal said he and his Kingdom Holding Co. rolled over a combined $1.89 billion in Twitter shares, making them the company’s largest shareholder after Musk. The news raised concerns among some lawmakers, including Sen. Chris Murphy, a Democrat from Connecticut.

Murphy tweeted that he is requesting the Committee on Foreign Investment — which reviews acquisitions of U.S. businesses by foreign buyers — to investigate the national security implications of the kingdom’s investment in Twitter

“We should be concerned that the Saudis, who have a clear interest in repressing political speech and impacting U.S. politics, are now the second-largest owner of a major social media platform,” Murphy tweeted. “There is a clear national security issue at stake and CFIUS should do a review.”

Having taken ownership of the social media service, Musk has invited a group of tech-world friends and investors to help guide the San Francisco-based company’s transformation, which is likely to include a shakeup of its staff. Musk last week fired CEO Parag Agrawal and other top executives. There’s been uncertainty about if and when he could begin larger-scale layoffs.

Those who have revealed they are helping Musk include Sriram Krishnan, a partner at venture capital firm Andreessen Horowitz, which pledged back in the spring to chip in to Musk’s plan to buy the company and take it private.

Krishnan, who is also a former Twitter product executive, said in a tweet that it is “a hugely important company and can have great impact on the world and Elon is the person to make it happen.”

Jason Calacanis, the venture capitalist who tweeted the poll about whether users would pay for verification, said over the weekend he is “hanging out at Twitter a bit and simply trying to be as helpful as possible during the transition.”

Calacanis said the team already “has a very comprehensive plan to reduce the number of (and visibility of) bots, spammers, & bad actors on the platform.”

And in the Twitter poll, he asked if users would pay between $5 and $15 monthly to “be verified & get a blue checkmark” on Twitter.

Twitter is currently free for most users because it depends on advertising for its revenue.