A top Republican senator said Tuesday he does not necessarily want to pass legislation regulating Facebook amid concerns about user privacy.

"I'm not rushing to do that," Senate Commerce Committee Chairman John Thune told CNBC's "Squawk Box."

His comments came ahead of Facebook CEO Mark Zuckerberg's Tuesday afternoon testimony before Thune's committee and the Senate Judiciary Committee. Zuckerberg will face questions about the revelation that consulting firm Cambridge Analytica may have misused the personal information of up to 87 million people. He will also likely get grilled about the use of his platform on Russian efforts to meddle in the 2016 election.

Thune, the third-ranking Senate Republican, said he hopes to find out at the hearing how far-reaching the misuse of personal data is. The South Dakota senator also wants to find out what Facebook is doing on its own to prevent the abuse of user information.