The hearing “must be constructive and focused on what matters most to the American people: how we work together to protect elections,” Twitter said in a tweet in its policy channel.

The hearing will come less than a week before Election Day. It marks a new bipartisan initiative against Big Tech companies, which have been under increasing scrutiny in Washington and from state attorneys general over issues of competition, consumer privacy and hate speech.

The executives’ testimony is needed “to reveal the extent of influence that their companies have over American speech during a critical time in our democratic process,” said Sen. Roger Wicker, a Mississippi Republican who heads the Commerce Committee.

Facebook, meanwhile, is expanding restrictions on political advertising, including new bans on messages claiming widespread voter fraud. The new prohibitions laid out in a blog post came days after President Donald Trump raised the prospect of mass fraud