WASHINGTON – U.S. Sen. Amy Klobuchar has emerged as a high-profile critic of Facebook, as she pushed Tuesday for the company's top leader to appear before Congress to account for a massive breach of personal data related to the last election.

The Minnesota Democrat wants Mark Zuckerberg, co-founder and CEO of the social media giant, to testify before the Senate Judiciary Committee about how the company will protect privacy after revelations that the personal information of 50 million users was exploited by a Russia-linked data analytics firm working to get Donald Trump elected in 2016.

"They keep saying, 'Trust us, we can take care of our own people and our own website,' " Klobuchar said in an interview Tuesday. "Well, that's not true ... That's the attitude that got them in trouble."

Klobuchar and a Republican colleague, Sen. John Kennedy of Louisiana, are calling on Judiciary Chairman Sen. Chuck Grassley, R-Iowa, to hold a hearing with Zuckerberg and executives of other major tech companies amid ongoing investigations of Russian agents meddling in American campaigns, including through social media posts aimed at influencing electoral outcomes. Concerns are likely to grow as the November 2018 midterm elections approach, with intelligence officials warning that Russia is likely to attempt more meddling.

Facebook is conducting a comprehensive internal and external review as it works to determine the accuracy of claims that the compromised data in question still exists, said Paul Grewal, Facebook vice president and deputy general counsel, in a statement.

Alexander Nix, CEO of the Trump-affiliated data mining firm Cambridge Analytica, was suspended on Tuesday. The chairman of the British Parliament's media committee, Damian Collins, said the committee has repeatedly asked Facebook how it uses data, and the company has been misleading.

"It's incredibly important that they come and testify under oath to tell the American people what happened on their platforms, and what steps they are taking to ensure that this never happens again," said Fred Wertheimer, president of Democracy 21, a D.C.-based nonprofit that pushes for government transparency.

He added: "If they're not prepared to voluntarily come, they should be subpoenaed."

Plenty of other chief executives have testified before Congress, from the heads of tobacco companies in the 1990s to the CEOs of auto manufacturers during last decade's financial crisis. The CEOs of Delta and Northwest airlines testified before the Judiciary Committee in 2008 about a proposed merger that drew antitrust concerns.

Some executives have also declined to appear, such as the chief executive of the pharmaceutical company Mylan in 2016 amid a controversy about overbilling Medicaid for the lifesaving device EpiPen.

"The tech companies seem to think they're in some special status that they don't have to do that, and I think there's going to be a drumbeat of 50 million people that want to see them," Klobuchar said Tuesday on MSNBC's "Morning Joe."

At last fall's Judiciary Committee hearing, Facebook, Google and Twitter were represented by attorneys — including at a Senate hearing about whether Russian agents used social media sites to try to influence the 2016 presidential election.

At that hearing, Klobuchar asked Facebook lawyer Colin Stretch if he supported her proposal to subject online political ads to the same disclosure requirements as those on radio, print and TV. It would also require online platforms to make reasonable efforts to ensure that foreign agents aren't purchasing ads to influence American campaigns.

Stretch replied that Facebook had drawn on the legislation to inform its announcement on political ads' transparency and disclosure requirements, and he said the company was ready to work with Klobuchar on the bill.

Klobuchar said she was frustrated that tech companies stopped short of endorsing the proposal. Months later, it hasn't moved in Congress, and among Republican legislators, only Sen. John McCain of Arizona has signed on as cosponsor.

"I think you do enormous good, but your power sometimes scares me," Kennedy said to Stretch last fall, in reference to Facebook.

A Grassley spokesman said that he has not made a decision about the request from Klobuchar and Kennedy. Grassley has a staff briefing with Facebook scheduled for Wednesday.

"The chairman is currently gathering information and taking steps to inform any action by the committee," Grassley spokesman Taylor Foy said in an e-mail.

Klobuchar said she wants the Judiciary Committee to hold a hearing this spring, before campaigning for the midterm elections begins in earnest. She predicts a record number of "slimy ads" on Facebook and other websites, including in Minnesota, which will have some of the most competitive congressional races in the country. The governor's race and two Senate elections will also heighten the political stakes.

She said her first questions to Zuckerberg at a hearing would be: "How are you going to protect the privacy of the hundreds of millions of subscribers that you have? ... How are you going to not just respond in a PR fashion to these crises but change your business model?"

The Associated Press contributed to this report.