Democrats on Capitol Hill are launching new efforts to prevent Russians and other foreigners outside the U.S. from using social media to interfere in future American elections.

House and Senate Democrats plan to send a letter to the Federal Election Commission this week asking them to consider new rules that would prevent foreigners from using online advertising platforms like Facebook and Twitter to influence voters.

The letter will likely be sent and made public on Wednesday, Daniel Jacobs a spokesperson for Rep. John Sarbanes, the chair of the Democracy Reform Task Force, an initiative of House Democrats, told CNN.

Sen. Mark Warner’s office is also looking at crafting legislation that would require disclaimers on who paid for advertisements, Rachel Cohen, one of his spokespeople, told CNN.

The efforts come two weeks after Facebook informed Congress that it had sold more than 3,000 ads to accounts linked to a Russian troll farm between June 2015 and May 2017.

In response to a search warrant, Facebook handed over copies of the ads and information about the relevant accounts to Special Counsel Robert Mueller, who is conducting an investigation into Russian meddling in the 2016 election.

Some members of Congress, meanwhile, are shifting at least part of their attention to regulations that might help prevent foreign meddling in future U.S. elections.

Facebook sources who spoke on the condition of anonymity said they anticipate that Congress will seek requirements for disclaimers on online political ads. Such disclaimers would identify the account that purchased any given ad, similar to political ads on television. The sources said they were not terribly concerned about disclaimer regulations, given that it is already standard for television and radio.

Political ad buyers are already expressing concerns that such requirements would not go far enough given the myriad ways of advertising on social media.

“The problem with the FEC and potential regulation talk from members of Congress is that they aren’t going far enough and it seems like they’re taking a TV filter and applying it to ad spends on digital,” Chris Nolan, a Democratic political ad executive, told Axios on Tuesday.

CNNMoney (Los Angeles) First published September 19, 2017: 7:38 PM ET