Facebook's attempts to stop foreign governments from buying political ads on its platform appear to have major loopholes—and two Democratic senators are not happy.

On Friday, Sens. Amy Klobuchar and Mark Warner called on Facebook to fix the problem, which can reportedly let anyone buy political ads under almost any name you like, including ISIS or Vice President Mike Pence.

"It is increasingly clear that major gaps exist in Facebook's efforts, potentially allowing adversaries to exploit your platform with continued disinformation efforts," the senators wrote in a letter to Facebook CEO Mark Zuckerberg about the problems.

In April, Zuckerberg said Facebook would verify the buyers of political and issue-based ads on the platform. To get verified, you need to supply a residential mailing address and a picture of a US passport or driver's license, along with the last 4 digits of your Social Security number.

More From PCmag

In addition, Facebook began requiring political ads to list who sponsored the advertisement. The problem is that authorized political ad buyers can place almost whatever text they want in the "paid for by" field for the ad, according to The New York Times. This allowed one anonymous buyer to run attack ads against a Democratic congressional candidate in Virginia on Facebook using the name "A freedom loving American Citizen exercising my natural law right…"

Vice News tested the system using the names of all 100 sitting US senators, including Mitch McConnell and Chuck Schumer, and succeeded.

"The fact Facebook's new security tools allow users to intentionally misidentify who placed political ads is unacceptable," Sens. Klobuchar and Warner wrote. The loopholes also suggest Facebook is failing to use human reviewers to vet political ads, the senators added.

In response, Facebook told PCMag that it's working to stop the potential abuse. "Inaccurate 'paid for by' labels violate our policies. On top of our existing proactive checks, when alerted to deceptive labels, we investigate and remove them," director of product management Rob Leathern said in a statement.

"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," he added.

The company created an archive where you can look up all the political ads served on Facebook. The searchable archive also provides a breakdown of the top ad buyers, how much was spent, and what ads were placed. But at this point, it's up to the buyer if they want to publicly disclose who they really are.

Simply checking the IDs of political ad buyers also may not enough to stop foreign governments from gaming the system. Earlier this year, the US government indicted 13 Russian nationals for exploiting social media in an attempt to influence voters during the 2016 US election. Allegedly, the Russians stole the identities of several US citizens to help them buy ads over the social media sites.

This article originally appeared on PCMag.com.