At a Senate Judiciary markup on Thursday morning, Sen. Amy Klobuchar (D-MN) said she would send a letter to Facebook and the Justice Department regarding concerns raised yesterday that the company might be violating campaign finance rules. Her criticism follows an explosive report from The New York Times yesterday that documents how Facebook’s leaders handled the fallout of the 2016 election.

At the markup, Klobuchar said that she was concerned that Facebook reportedly hired an opposition research firm in the aftermath of the 2016 election “to go after its critics.” The Times story named a Republican firm called the Definers Corporation, which was reportedly hired to target the company’s critics and competitors by tying protestors to the highly influential Democratic donor, George Soros.

Later Thursday afternoon, Klobuchar, along with Sens. Richard Blumenthal (D-CT), Chris Coons (D-DE), and Mazie Hirono (D-HI), sent a letter addressed to Deputy Attorney General Rod Rosenstein asking for the Justice Department to “expand any investigation into Facebook and Cambridge Analytica to include whether Facebook – or any other entity affiliated with or hired by Facebook – retaliated against critics or public officials seeking to regulate the platform, or hid vital information from the public.”

At the Judiciary markup earlier in the day, Klobuchar said that she was concerned that if Facebook was taking actions against its critics, the company could be violating campaign finance rules. “Whether they hired someone to work on this, we don’t know what happened and it wasn’t reported in that fashion. It could also have other legal ramifications,” she said.

Klobuchar also invoked The Honest Ads Act, of which she is a cosponsor. The bill would require Facebook to open a public database with records of every political ad purchased on its platform and combat foreign interference in elections. It was introduced last fall after it was discovered that Russian agents were using Facebook to spread misinformation through the company’s ads platform. According to the Times, Sheryl Sandberg, Facebook’s chief operating officer, reached out to Klobuchar to discuss the legislation. Reportedly, Klobuchar backed off from criticizing the company after the discussion, having not posted any harsh statements on her Facebook page.

Facebook lobbied heavily in connection with the Honest Ads Act, according to public records. Separately, Klobuchar has received nearly $20,000 in campaign contributions from Facebook in 2018.

After yesterday’s report, the presidential-hopeful might be looking to revamp her criticism and push harder for the Honest Ads Act. “I have tried very hard to get more support for this bill,” Klobuchar said. “I personally think post-election, this is an ideal time to move forward with this legislation. I appeal to my friends on the other side of the aisle.”

In an interview with The Verge last month, Sen. Mark Warner (D-VA), a cosponsor of the legislation, said that the primary reason the bill hasn’t been brought to the floor was because Majority Leader Mitch McConnell (R-KY) is opposed to holding votes on any legislation that involves campaign finance.

According to the senators, the Federal Trade Commission, Securities and Exchange Commission, the FBI, and the Justice Department are already conducting investigations into Facebook and its failures to secure user data. With this letter, the senators are prompting officials to deepen the investigations they already have open to include any further information that is uncovered into Facebook’s behavior.

“Given the staggering amount of data that Facebook has collected on both its users – even people who have not consented to use of the platform – these allegations raise profound concerns about the company’s willingness to protect the public and our democracy,” the senators wrote.

Update 11/15/18 5:40 p.m.: Updated with information following the release of the letter.