A pair of Democratic senators on Friday pressed Facebook to fix its political ad transparency tools that reportedly allow users to make misleading claims about who is purchasing an ad.

“The fact that Facebook’s new security tools allow users to intentionally misidentify who placed political ads is unacceptable," Sens. Amy Klobuchar (Minn.) and Mark Warner (Va.) wrote in a letter to CEO Mark Zuckerberg. "That Facebook is unable to recognize ads connected to a well-established foreign interference operation is also deeply troubling.”

The letter follows reports in which Vice News was able to purchase ads on Facebook and attribute them to being paid for by Vice President Pence, the Islamic State in Iraq and Syria and all 100 U.S. senators.

The two Senate Democrats also used their letter to promote their legislation, The Honest Ads Act, which aims to create more transparency in political ads by holding social media firms like Facebook to the same standards as traditional media like TV, radio and newspapers.

“You have committed to implementing transparency measures similar to those that the Honest Ads Act would require; however, your company is currently failing to carry out the basic disclosure and disclaimer provisions of the legislation,” Klobuchar and Warner wrote.

Facebook said that it supports the lawmakers' goals and is working to increase transparency on its platform.

"This publicly-available ad archive is valuable for news organizations, regulators, watchdog groups, and the public, and it’s a way we’re also held accountable – even if it means our mistakes are on display," a Facebook spokesperson said. "We’re exploring additional checks to help prevent abuse and will respond to requests from law enforcement and election officials now and in the future if new requirements arise.”

The two lawmakers introduced their legislation in late 2017, following revelations that Facebook’s platform, along with Twitter and YouTube, had been manipulated by Russian trolls in an attempt to influence the 2016 presidential election.

At the time, Klobuchar and Warner said their bill would help make it harder for foreign governments to take similar action in the future because the transparency requirements would force social media companies to reveal who is paying for an ad.

The bill has not gained traction in the GOP-controlled Senate, but Facebook has committed to voluntarily regulating itself in a manner similar to some of the provisions in the legislation.

But despite its commitment, Vice News and ProPublica say they have found loopholes in Facebook’s transparency rules.