The ideas echo many of the recommendations made in a House Justice Report last October led by David Cicilline, a Democrat from Rhode Island. However, its bill does not contain provisions to wind up past mergers and other structural reforms as recommended in its report.

Your bill, as well as other laws limiting the power of tech companies, will meet with stiff opposition. In 2020, technology companies again spent more than other industries in Washington. Facebook spent nearly $ 20 million on lobbying with lawsuits from federal and state officials, an 18 percent increase over the previous year. Amazon spent around $ 18 million on lobbying, up around 11 percent over the previous year.

Internet startups are also wary of regulations that could hamper their exit strategies for merging with larger companies, as well as changes in rules that could make them accountable for the content they host. Agriculture, pharmaceuticals, and other industries are also likely to resist changes to antitrust laws.

But the Democrats are also under pressure from the left. Progressive groups and some liberal lawmakers want to cut the biggest companies. In a sign of the battles ahead, these groups have raised concerns over the past few weeks about some potential candidates for top positions with antitrust authorities that they say are not aggressive enough against the industry.

“We hope the Senate Antitrust Subcommittee will work with the House Subcommittee to translate into law the full set of recommendations in the Digital Markets Report,” said Sarah Miller, executive director of the American Economic Liberties Project, a leftist. The leaning not-for-profit advocacy focused on fighting corporate power. “We won’t be shy when it comes to pushing for bolder approaches.”

Ms. Klobuchar says the new outrage over the role of social media in the January 6 attack on the Capitol has united lawmakers in their animus towards digital platforms, but for different reasons. Democrats are angry that Facebook, Twitter and YouTube allowed President Donald J. Trump and far-right groups to spread disinformation about the elections that sparked the riot. Republicans are motivated by the platforms’ decisions to expel Mr Trump and his far-right supporters.

Republican Ken Buck, Colorado Republican and senior member of the House of Representatives Antitrust Subcommittee, said he would work with Democrats on law, more hearings and research into the technology sector.