Democratic lawmakers are calling on Facebook, Twitter and other social media to alter the powerful algorithms that fuel their site, saying that they led to the attack on the Capitol and intensify fringe political beliefs.

"The algorithms Facebook uses to maximize user engagement on its platform undermine our shared sense of objective reality, intensify fringe political beliefs, facilitate connections between extremist users, and, tragically, lead some of them to commit real-world physical violence, such as what we experienced firsthand on January 6th," wrote Silicon Valley Congresswoman Anna Eshoo and New Jersey Congressman Tom Malinowski in a letter to Facebook CEO Mark Zuckerberg.

The two sent similar letters to Twitter CEO Jack Dorsey and the CEO of YouTube Susan Wojcicki and Google CEO Sundar Pichai. All were co-signed by dozens of congressmembers.

The attack on the Capitol has increased scrutiny of social media sites but officials will have difficulty drawing a line between speech that incites violence and muzzling political expression. Snap, Twitter, Facebook and other sites took down President Donald Trump's accounts in the days after a violent mob stormed the U.S. Capitol. Critics say the aggressive stance is too little, too late and it hasn't stemmed the tide as conspiracy theories and other extreme beliefs continue to proliferate.

"The algorithmic amplification and recommendation systems that platforms employ spread content that's evocative over what's true," Eshoo said in a statement. "The horrific damage to our democracy wrought on January 6th demonstrated how these social media platforms played a role in radicalizing and emboldening terrorists to attack our Capitol. These American companies must fundamentally rethink algorithmic systems that are at odds with democracy."

Eshoo sat on the powerful Communications & Technology subcommittee in the last Congressional session, during which she and Malinowksi introduced legislation to amend Section 230. The law governs the liability of internet intermediaries, including social media companies, for the content users publish on their platforms. The amendment would increase sites' liability for how their algorithms spread harmful or radicalizing content that leads to offline violence. She has said she will reintroduce it in this Congress.

See the full letters here:

• Letter to Mark Zuckerberg, Facebook
• Letter to Susan Wojcicki and Sundar Pichai, YouTube; Alphabet/Google
• Letter to Jack Dorsey, Twitter