Top: Facebook CEO Mark Zuckerberg (R), Amazon CEO Jeff Bezos (2nd R), bottom: Google CEO Sundar Pichai (L), Apple CEO Tim Cook (2nd L) are sworn in remotely during a House Judiciary subcommittee hearing on Capitol Hill, July 29, 2020, in Washington.
Top: Facebook CEO Mark Zuckerberg (R), Amazon CEO Jeff Bezos (2nd R), bottom: Google CEO Sundar Pichai (L), Apple CEO Tim Cook (2nd L) are sworn in remotely during a House Judiciary subcommittee hearing on Capitol Hill, July 29, 2020, in Washington.

WASHINGTON - The CEOs of four U.S. technology giants – Apple, Amazon, Facebook and Google – have fended off accusations from Congress of stifling competition, stealing ideas and censoring conservative political voices.

The CEOs testified remotely Wednesday at a hearing of the House Judiciary Antitrust Subcommittee, which has been investigating the companies with an estimated combined market value of $5 trillion.

"Many of the practices used by these companies have harmful economic effects. They discourage entrepreneurship, destroy jobs, hike costs and degrade quality. Simply put, they have too much power,” Rhode Island Democrat and subcommittee Chairman David Cicilline said Wednesday.

WATCH: Judiciary Committee Hearing

Amazon CEO Jeff Bezos – the world’s richest person – defended the online retailer’s practices and its dominant market share. Bezos told the lawmakers “80 percent of Americans have a favorable impression of Amazon overall.”

“There are now 1.7 million small and medium-sized businesses selling on Amazon,” Bezos said in his first appearance before Congress. “The trust customers put in us every day has allowed Amazon to create more jobs in the United States over the past decade than any other country.”

Google CEO Sundar Pichai testifies before the House Judiciary Subcommittee on Antitrust, Commercial and Administrative Law during a hearing on "Online Platforms and Market Power".

But a number of familiar U.S. retailers are in financial trouble, and some economists say Amazon is partially to blame.

Bezos repeated his denials that Amazon deliberately stole information from its online sellers so it could manufacture its own products and directly compete with its sellers.

“We have a policy against using seller-specific data to aid our private-label business. But I can’t guarantee to you that that policy hasn’t been violated,” Bezos said.

Google’s Sundar Pichai also denied accusations that his company steals from other businesses, specifically from Yelp, the customer review website.

“We conduct ourselves to the highest standards,” he said.

Republican Representative Jim Jordan of Ohio accused the big tech companies, including Facebook and Twitter, of being “out to get conservatives.” Users of both platforms come from a wide spectrum of political beliefs, but they can tailor their feeds to provide information from sources they prefer.

Amazon CEO Jeff Bezos testifies before the House Judiciary Subcommittee during a hearing on "Online Platforms and Market Power" in the Rayburn House office Building on Capitol Hill, in Washington, July 29, 2020.

"We're 97 days before an election … the power these companies have to impact what happens during an election, what people what American citizens get to see prior to their voting is pretty darn important,” Jordan said. “We all think the free market is great. We think competition is great. We love the fact that these are American companies. But what's not great is censoring people, censoring conservatives and trying to impact elections."

The companies have consistently denied all allegations of censorship and trying to manipulate the U.S. electorate.

Some antitrust experts have criticized U.S. lawmakers and regulators for what they say is weak government oversight of the tech giants, especially compared with stronger enforcement in Europe.

President Donald Trump, who has also been critical of the companies, tweeted Wednesday that “If Congress doesn’t bring fairness to Big Tech, which they should have done years ago, I will do it myself with Executive Orders.”

Lawmakers cannot charge tech companies with antitrust violations or attempt to break them into smaller entities. They can only pass laws and put pressure on regulators at the Federal Trade Commission and the U.S. Department of Justice to do more to enforce existing regulations.

As they consider how to address the business practices of these companies, Congress must take into account that while Apple, Google, Facebook and Amazon are the Who’s Who of internet firms, their businesses are not really the same.

Rep Jim Jordan, D-Ohio, speaks during a House Judiciary subcommittee on antitrust on Capitol Hill, July 29, 2020, in Washington.

The Justice Department is reportedly likely to bring antitrust lawsuits against Google. State regulators may join the Justice Department or pursue their own cases, according to reports.

VOA's Michelle Quinn contributed to this story.