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House lawmakers on Wednesday called for two top antitrust regulators to take more action against major tech companies, saying several of these companies have avoided serious scrutiny for years as they swallowed up competitors and consolidated power. They made the request during a hearing for the House Judiciary's Subcommittee on Antitrust, Commercial and Administrative Law, which has been holding a series of hearings dubbed Online Platforms and Market Power.

"Despite mounting evidence of illegal monopolization activity by some of the dominant platforms and numerous cases brought by international enforcers, US enforcers appear to be paralyzed," Democratic Rep. Jerrold Nadler said in an opening statement. "It has been decades -- decades -- since the Department of Justice or the Federal Trade Commission has brought a significant monopolization case in the tech sector."

Wednesday's hearing included just two witnesses: FTC Chairman Joseph Simons and Makan Delrahim, the assistant attorney general for the Justice Department's Antitrust Division. The tone was largely collegial, with the subcommittee's antitrust efforts becoming a rare case of bipartisan work in a polarized Capitol. There were also few people in the audience, perhaps owing to the hearing being overshadowed by the highly anticipated House impeachment public hearings kicking off the same day.

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Delrahim and Simons attended a similar hearing in September held by the Senate Judiciary Committee, pointing to just how much attention tech antitrust concerns have grown in Washington DC.

The hearing came as regulators and lawmakers have been shining a harsher light on many of the biggest US tech companies -- Facebook, Google, Amazon and Apple -- and their potential monopolies. So far, Facebook has publicly disclosed investigations into the social giant by both the Justice Department and the FTC, and Google disclosed a Justice Department investigation.

Added to that, the House Judiciary Committee and a group of state attorneys general are investigating these tech titans, too.

This work could have huge implications for the future of tech, potentially resulting in the breakup of dominant players like Facebook, the prevention of future tech mergers, or the creation of additional regulatory restrictions on tech giants. Regulators and lawmakers say they are pursuing this work to ensure customers can benefit from the growth of innovative new startups and healthy competition.

For their part, many major tech companies say they remain small players in their fields, such as Amazon being a fraction of global retail, and point to long lists of competitors in their markets.

While several committee members on Wednesday called for more regulatory action, Simons, from the FTC, warned that his agency lacked the authority to pursue more privacy-related enforcement. He said Congress would first need to enact privacy-focused laws, similar to the European Union's General Data Protection Regulation or the California Consumer Privacy Act.

"If you want us to do more on the privacy front, then we need more tools from you," he said.

Additionally, Republicans Jim Sensenbrenner and Doug Collins on Wednesday both warned of unintended consequences of new regulations and government overreach that could stifle innovation. For instance, Simons mentioned how Europe's GDPR may have ended up reinforcing market leaders there and suppressing new competitors.

"Proposals to break up big companies just because they are big risks throwing out the baby with the bathwater and are simply punishing success," Collins said.