Facebook and Twitter have agreed to testify at an upcoming Senate Intelligence Committee hearing on Russian interference during the 2016 elections, the companies confirmed Wednesday.

Both companies have already briefed House and Senate Intelligence Committees on their findings regarding Russian actors using their platforms to influence the presidential election.

Google was also invited to testify but has not confirmed whether it will send a representative to the hearing, which is scheduled for Nov. 1.

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The House Intelligence Committee’s top Democrat, Rep. Adam Schiff Adam Bennett SchiffTop Democrats call for DOJ watchdog to probe Barr over possible 2020 election influence Overnight Defense: Top admiral says 'no condition' where US should conduct nuclear test 'at this time' | Intelligence chief says Congress will get some in-person election security briefings Overnight Defense: House to vote on military justice bill spurred by Vanessa Guillén death | Biden courts veterans after Trump's military controversies MORE (Calif.), says a Google briefing with his committee is “imminent,” but has not shared a date. That committee plans to hold a hearing with the company in October but there is no set date.

Facebook and Twitter on Wednesday said they are proactively working with lawmakers to cooperate in their investigations.

"As we noted in our blog post last week, we are cooperating with these investigations in Russian interference in the 2016 election,” a Twitter spokesperson said in an emailed statement.

“Twitter deeply respects the integrity of the election process, and will continue to both work with the investigations and to share details of our findings with the public as we are able."

Facebook revealed last month that Russian linked groups spent $100,000 on election ads.

On Monday, the company turned over 3,000 advertisements purchased by the Internet Research Agency, a group tied to the Kremlin, to congressional investigators. The election-related ads were purchased in 2015 and 2016.

The company is also taking steps to improve transparency about who purchases advertising.

But some lawmakers don’t think Facebook and Twitter have done enough.

After Twitter briefed the Senate Intelligence Committee last week, the panel's top Democrat, Sen. Mark Warner Mark Robert WarnerIntelligence chief says Congress will get some in-person election security briefings Overnight Defense: Trump hosts Israel, UAE, Bahrain for historic signing l Air Force reveals it secretly built and flew new fighter jet l Coronavirus creates delay in Pentagon research for alternative to 'forever chemicals' House approves bill to secure internet-connected federal devices against cyber threats MORE (Va.) called the company’s efforts “deeply disappointing."

“Their response was frankly inadequate on almost every level,” he said.

On Monday, Schiff and Sen. Richard Blumenthal (D-Conn.) called for Facebook to make the 3,000 Russian ads available to the public. Facebook has not responded directly to that request.

Schiff and Warner said they have many questions for Twitter, Google and Facebook.

“How thorough has their investigation been?” Schiff said. “What more remains to be done? These are the questions we’ll be posing at the open hearing.”

This story was updated at 3 p.m.