At a separate Senate hearing earlier on Wednesday, Dorsey and Facebook Chief Operating Officer Sheryl Sandberg faced threats of legislative action from skeptical lawmakers over what many members of Congress see as a failure to block fake accounts and other foreign efforts to influence USA politics.
Facebook's No. 2 executive, Sheryl Sandberg, and Twitter's CEO, Jack Dorsey, testified before the Senate intelligence committee, but there was an empty chair for Google's parent Alphabet, which refused to send its top executive.
The statement from Dorsey released by a House panel covered questions about foreign influence operations on social media as well as accusations of political bias.
At the start of the hearing Senator Mark Warner, the committee's Democratic vice chairman, said the companies were not doing enough to stop the flow of foreign influence and threatened Congressional action.
Sandberg, in her prepared remarks, detailed how Facebook was addressing the problem but reiterated that the company was slow to spot it.
This will be the first time Sandberg has publicly faced significant questioning about Facebook's role in the 2016 election.
Jim Jordan, Matt Gaetz and Mark Meadows - were "shadow banned" this summer from Twitter when their names didn't automatically pop up when typing in the search box, they complained.
"What I hope to see from the two executives who are appearing before the committee is a similar seriousness and transparency and a focus on recognizing that while they may have taken steps, this is an ongoing problem and much remains to be done", Rosenberger said.
The Menlo Park, California-based company revealed a year ago that a Russian internet agency had used the platform to try to influence the 2016 US presidential election.
And Dorsey said Twitter was "unprepared and ill-equipped" to defend users against nefarious actors that have gamed the platform's services.
"I'm skeptical that, ultimately, you'll be able to truly address this challenge on your own".
"That's on us", she wrote.
Conspiracy theorist Alex Jones held a press conference outside the Senate hearing room as the testimony began to criticize the social media companies for banning him and his website Infowars from their platforms.
Sandberg and Dorsey both agreed with Wyden that the issue should be viewed as a top national security priority.
Google, which was also invited to the hearing, did not send a representative.
Though no Google representative is expected to testify as of this report, in a blog post Tuesday Google Senior Vice President for Global Affairs and Chief Legal Officer Kent Walker said he would still be in Washington to separately brief lawmakers on Google's efforts and will be submitting written testimony to the Senate committee.
Lawmakers also criticized Alphabet Inc's (GOOGL.O) Google for refusing to send top executives to testify in the Senate on foreign efforts to influence US politics, with just weeks before the November 6 congressional elections.