Senate Democrats are pressing the Federal Election Commission to issue new rules requiring disclaimers on all online political ads.

“Clear and conspicuous disclaimers on all political and issue advertisements are necessary to ensure the level of transparency and accountability that a healthy democracy demands,” Senators Amy Klobuchar (D-Minnesota), Mark Warner (D-Virginia) and 22 others say in a letter sent this week to FEC Chair Ellen Weintraub. “Americans deserve to know who is paying for online advertisements placed to influence their vote, regardless of whether those advertisements run on the radio, television, or online.”

Last year, the FEC released two proposals for ways in which campaigns could disclose who paid for political ads on Facebook, Google and other platforms. One proposal calls for information about the sponsor in the ad itself. The second would allow that information to be presented in other formats, including via in-ad links.

Those rules would only apply to paid ads that promote or criticize candidates for elected office -- but not ads that focus on issues, without referencing candidates.

Klobuchar and the other lawmakers say it's “unacceptable” that the FEC hasn't yet finalized new rules.

“Given the dramatic increase in online spending and the fact that intelligence officials continue to warn that online platforms will be used to undermine elections, it is unacceptable that the FEC has failed to issue a final rule,” they write.

The lawmakers are asking Weintraub when the FEC expects to issue a final rule on disclaimer requirements and what has caused the delay, among other questions.

The FEC began considering new rules after revelations surfaced that Russian operatives purchased campaign ads that appeared on Facebook, Google and Twitter during the 2016 presidential election cycle.

Existing FEC rules require disclaimers on certain types of online ads, but not to the same extent as ads on TV or the radio. For instance, Google is allowed to run pay-per-click political ads without including disclaimers in the copy, provided that the text displays the URL of the sponsor's site, and that the landing page has a disclaimer.