Senate lawmakers voted Thursday to authorize a subpoena that could compel the chief executives of Facebook and Twitter to testify before a congressional hearing exploring their content-moderation practices, ramping up the war between Republicans in Washington and tech giants in Silicon Valley less than two weeks before the 2020 election.

GOP leaders on the Senate Judiciary Committee voted unanimously to approve the formal summons targeting Facebook’s Mark Zuckerberg and Twitter’s Jack Dorsey, a move that the panel’s chairman, Sen. Lindsey O. Graham, said would provide his colleagues “leverage to secure their testimony” at an unspecified date.

The subpoena itself specifically says lawmakers seek to press the two tech executives over their “suppression and/or censorship” of reporting published by the New York Post about Hunter Biden, the son of Democratic candidate and former vice president Joe Biden. Facebook and Twitter each limited the spread of the Post’s story — with Twitter initially blocking links outright before relenting — out of concern about the origins of the information.

No Democrats voted on the subpoena: Party lawmakers did not attend the session in protest of the committee’s earlier vote to advance Amy Coney Barrett’s Supreme Court nomination to the full Senate for a confirmation vote.

But the subpoena threat — which still must be sent to the tech companies — adds to the industry’s political headaches at a time when many top Republicans, including President Trump, continue to snipe at social media sites over allegations they censor conservatives online. GOP leaders have ratcheted up their attacks as Facebook and Twitter seek to crack down on harmful election misinformation, including misleading posts about voting from the president himself.

Zuckerberg and Dorsey are set to join Google CEO Sundar Pichai at a previously scheduled hearing Wednesday before the Senate Commerce Committee. Republicans there similarly voted to subpoena the tech executives before ultimately obtaining their voluntary commitment to testify. The hearing is expected to be highly political and wide-ranging — touching on everything from content moderation to the government’s recent antitrust lawsuit targeting Google.

The congressional scrutiny comes as Republicans ratchet up their campaign to rethink Section 230, a portion of federal law that spares social media sites from being held liable for the content posted by their users — or their decisions about what to leave up or take down. GOP lawmakers have taken aim at the decades-old rules in response to concerns about political bias, charges for which they have offered little evidence and one that Facebook, Google and Twitter staunchly deny.

Facebook did not respond to a request for comment, and Twitter declined.