Social media companies continued to face pressure over exploitation of their platforms, as lawmakers on Wednesday chastised Facebook and Twitter for failing to explain the role pro-Russian accounts played in a large online campaign to release a classified memo related to the Russia investigation.

In a new letter to Facebook and Twitter, two top congressional Democrats, Sen. Dianne Feinstein and Rep. Adam B. Schiff, said the companies had not adequately answered their questions from last week about whether Kremlin-affiliated accounts had promoted a hashtag campaign called #ReleaseTheMemo. The highly politicized memo alleges that the FBI abused its surveillance authority as it probed Russian meddling in the 2016 election.

“We are no closer to understanding Russia’s continued interference in our democratic affairs,” the lawmakers wrote. “We cannot wait another year to learn how Kremlin-linked trolls and bots are currently exploiting your platforms to influence debates going on in Congress today.”

Feinstein and Schiff, both of California, also released the responses Facebook and Twitter sent to them last week following their initial letter, which they called inadequate and incomplete. Facebook's two-paragraph written statement didn't address the use of the hashtag on its platforms, and it pointed out that reports into the spread of the hashtag referred only to Twitter.

Twitter said in its response that a “preliminary analysis of available geographical data for Tweets with the hashtag #ReleaseTheMemo ... has not identified any significant activity connected to Russia with respect to tweets posting original content to this hashtag.”

The questions over Russia’s involvement emerged earlier this month when researchers reported that the hashtag was being tweeted frequently by hundreds of Twitter accounts known to spread Russian disinformation. The tool, called Hamilton 68: Tracking Russian Influence Operations on Twitter, is a project of Alliance for Securing Democracy, a U.S.-based nonprofit group that examines efforts by foreign nations to interfere in democratic institutions.

#ReleaseTheMemo was the top hashtag used by the 600 tracked pro-Russia accounts over the past 48 hours, a position it has held for several days. “TweetTheMemo” and “NunesMemo” and “TheMemo” were also popular. (Rep. Devin Nunes (R-Calif.) is the chairman of the House Intelligence Committee that wrote the memo). A Fox News article about the Nunes memo was the top trending article Wednesday on Facebook.

The Democratic lawmakers said Twitter's analysis was too restrictive. Numerous researchers, and Twitter itself, have previously said that many accounts that amplify Russian disinformation often mask their locations.

Additionally, Twitter’s analysis of original posts appeared to neglect the role of reports, or retweets, in spreading the hashtag, lawmakers said. Twitter pointed out that several prominent accounts maintained by U.S. users had tweeted the hashtag in January, which could have caused it to trend.

Twitter did not respond to questions from The Washington Post about why it only looked at geography as a factor in determining a Russia connection and why it only examined tweets and not retweets. The company has previously acknowledged that Russian accounts frequently retweet narratives that were already part of the U.S. political debate.

The creators of the Hamilton dashboard don't claim that the accounts they follow originate in Russia, only that these accounts amplify and promote themes that are of interest to the Russian government.

Both companies declined to provide additional comment to The Post and referred inquiries back to their original letters.

The campaign to release the memo has turned into striking political standoff in recent days. President Trump indicated he would probably release it, while the FBI openly challenged its validity and opposed efforts by Republican lawmakers to publish it. The FBI, in a statement Wednesday, said it had “grave concerns” about the accuracy of the memo.

Lawmakers pressed the companies to explain the methodology of their analyses and to disclose the volume and frequency of postings on the topic, and how many legitimate account holders had been exposed to the campaign. They set a new deadline of Feb. 7 for the companies to respond.

Separately, Twitter on Wednesday said it was notifying 1.4 million users that they had followed accounts linked to the Russian disinformation campaign or had shared related content with their followers by retweeting, quoting or replying to their messages.