WASHINGTON — Political advertisements on Facebook would have to include disclosures showing who paid for them, under two draft legal opinions the nation’s federal election regulators are scheduled to take up this week.

If the Federal Election Commission (FEC) votes to adopt either opinion at its Thursday meeting, it would mark the government’s first major move to regulate political advertising on social media following revelations that Kremlin-tied groups used ads on Facebook and other platforms in an effort to sway the 2016 presidential election.

“Addressing the issue of Internet disclaimers is just one small step — but a small step in the right direction — towards getting the American people the information they need to be able to assess the information they are receiving over the Internet,” said Ellen Weintraub, a longtime Democratic Federal Election Commission member who has advocated for the regulation.

Transparency advocates warn that far more is needed and are pushing Congress to pass sweeping regulations as online advertising grows in politics. Last year, digital advertising to influence elections topped $1.4 billion, swamping the $159 million spent on online ads during the 2012 elections, according to data compiled by the media-tracking firm Borrell Associates.

A pair of bills introduced in House and Senate in October, dubbed the Honest Ads Act, would go further than what federal regulators will consider this week. The bills would require social-media companies to make copies of political ads available for public review and would extend a slew of campaign-finance laws that currently apply to television and radio ads to the digital world. It also requires all advertising platforms — whether broadcast or digital — to "make reasonable efforts" to ensure foreign interests aren't paying for political ads.

Federal law bars foreign nationals from spending in U.S. elections.

“Transparency isn’t enough here,” said Alex Howard, deputy director of the nonprofit Sunlight Foundation. “There has to be some accountability for bad actors within the system.”

Earlier this year, Facebook disclosed that it had identified more than $100,000 in political ads purchased by a Russian company with ties to the Russian government. Most of the 3,000 ads focused on hot-button issues such as immigration and gay rights. They ran between June 2015 and May 2017.

Facebook has promised to take voluntary steps to make political advertising on its platform more transparent. The social-media giant has not endorsed the bills in Congress.

In comments to the FEC, however, Facebook’s top lawyer Colin Stretch said the company is open to "further guidance" from the agency, in part, to ensure that Facebook’s voluntary moves to reveal more about its advertisers doesn’t push potential customers “who wish to avoid disclosure to use other, less transparent platforms.”

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It’s not guaranteed that the Federal Election Commission, often bitterly divided along partisan lines, will approve the disclosure requirement this week. But there are indications that the commission is open to tackling digital advertising in the aftermath of the 2016 election. After years of stalemate on the issue, commissioners in September voted unanimously to re-start writing rules that broadly address online ads.

Thursday’s meeting on disclaimers won’t address those broader rules but is aimed at responding to a narrow request from a political group, called Take Back Action Fund, for guidance on what disclaimers it must run on its Facebook ads if they call for the election or defeat of a specific candidate.

FEC rules require the agency to respond to requests for such legal opinions within 60 days, and the commission’s actions, or inaction, on so-called advisory opinion requests often become the de facto legal road map followed by donors, candidates, parties and others engaged in federal politics.

In 2011, Facebook asked the FEC for an advisory opinion to exempt the company from the disclaimer requirements, which long have applied to television, radio and print political ads. The commission deadlocked on the issue, however.

If the agency adopts the new legal opinion this week, Weintraub said it would clarify rules she believes that Facebook and others firms should have been following all along.

“There really is no defensible position to be taken anymore to say, ‘Oh no, we should leave this area completely free of regulation,’ ” Weintraub said. “We’ve left the door open to some fairly egregious behavior, and we really need to shut that door before the next election rolls around.”