"I'm not sure if having five more Facebooks, if you broke up Facebook into five component parts, or any of these other large social media or technology companies, makes as much sense as regulating them, given the power that they have," O'Rourke said Wednesday in response to a question from CNN.
Warren's far-reaching proposal, which she outlined in a post on Medium, would see companies like Amazon and Google designated as platform utilities that could not own marketplaces and participants in the marketplaces. For example, Amazon would no longer be allowed to own Amazon Basics. In addition, it would involve the unwinding of mergers such as Facebook's purchase of Instagram and Google's purchase of Nest or Ad Sense.
"The way in which they can be used wittingly or not to undermine our democracy and affect the outcomes of our elections," O'Rourke said. "[Regulation] is the path I would prefer this country to take, but I am aware how grave this challenge is right now for the reasons I just described."
In announcing her proposal, Warren noted that "nearly half of all e-commerce" in the U.S. goes through Amazon, while more than 70 percent of all Internet traffic comes from sites "owned or operated" by Google and Facebook, including sites such as YouTube and Instagram.
In his remarks, O'Rourke also made a joke about the fine-print filled, extremely long terms of service agreements touted by tech companies that most average Americans don't read.
"Our privacy has been violated, we're confronted with 37-page user agreements, and I want to asterisk that in case anybody checks -- I don't know how long the user agreements are, I don't go through them, I just say I agree like most people do without knowing a word that's in them," O'Rourke said. "[We need to] regulate them more seriously."
Other Democrats running in 2020 have offered their own takes on the backlash against Big Tech.
Pete Buttigieg, the 37-year-old mayor of South Bend, Ind., who formed an exploratory committee in January, told Axios that firms like Facebook and Google have "monopoly power" and said there's a need for more stringent regulations at the federal level.
Vermont Sen. Bernie Sanders has regularly slammed Amazon over its treatment of workers, and New Jersey Sen. Cory Booker, long seen as a friend of Silicon Valley, recently said tech companies need to take responsibility for "spreading hate" in the wake of the New Zealand mosque massacre that was livestreamed on Facebook and then spread virally on multiple social media platforms.
A recent Morning Consult poll found that 52 percent of voters, including 49 percent of Republicans, said regulating Big Tech should be a "top" or "important" priority for Congress.
Fox News' Chris Ciaccia contributed to this report.