Notably absent from the hearing: anyone from Google or its parent company, Alphabet.
"Any suggestion that Jack made or overruled any of these decisions is completely and totally false", Twitter's chief legal officer, Vijaya Gadde, said in a statement.
"We were too slow to spot this and too slow to act", Sandberg will say.
Dorsey, sporting a straggly beard, nose ring and open-collared shirt, insisted Twitter's monitoring has tightened, including notifying law enforcement last month of accounts that appeared to be located in Iran. Richard Burr, R-N.C., said Google doesn't "understand the problem" if it doesn't want to work with the government to find solutions.
"Clearly, this problem is not going away". Though Burr added, "I'm not sure your success is the big story here". On Tuesday it released written "testimony" describing the company's efforts to combat influence operations. And I'm skeptical that, ultimately, you'll be able to truly address this challenge on your own. "We believe that we have a responsibility to prevent the misuse of our platforms and we take that very seriously", said Walker, who has previously testified before the committee and was the official Google hoped to send again.
There might also be overall uncertainty about the future of Twitter, now that Dorsey has publicly said the company is fundamentally rethinking core parts of the business.
Dorsey said it was "unacceptable" that she was not told.More news: California Streamin': State Gets Tough on Net Neutrality
"We were too slow to spot this and too slow to act", Sandberg said during the Senate hearing, addressing Russian attempts to interfere in the 2016 USA presidential election.
Trump told the conservative publication that social media companies had already interfered in the 2018 elections. The report gave no other details.
The Senate Intelligence Committee has been looking into efforts to influence U.S. public opinion for more than a year, after United States intelligence agencies concluded that Kremlin-backed entities sought to boost Republican President Donald Trump's chances of winning the White House in 2016.
The testimony comes as some Republicans say conservatives have been censored on social media.
Twitter's Dorsey, meanwhile, is slated to testify before the House Energy and Commerce Committee in addition to the Senate.
"Twitter does not use political ideology to make any decisions, whether related to ranking content on our service or how we enforce our rules", Dorsey said in prepared remarks to a congressional hearing with U.S. technology giants. Some Republicans, including President Trump, have pushed the idea ahead of the elections that Twitter is "shadow banning" some in the GOP because of the ways search results have appeared.
For more coverage of congressional hearings on social media, see the TOPLive blog. Instead, a spokesperson for the committee said they may just leave a chair empty next to Sandberg and Dorsey.
In a statement to HuffPost, Google said it's been diligent in briefing lawmakers on the political interference issue in the past.