Democratic Sen. Amy Klobuchar is finally in power, and she's not wasting a second.

Klobuchar, the new chairwoman of the Senate Judiciary antitrust subcommittee, on Thursday will introduce sweeping legislation to reform the country's trust-busting laws, with a special focus on reining in the unprecedented power of the largest tech companies.

Klobuchar's Competition and Antitrust Law Enforcement Reform Act of 2021, a refurbished version of bills she's introduced over the last few years, is the most serious legislative salvo against Big Tech in years. It comes as Democrats assume power over both chambers of Congress and the White House — and Klobuchar has made it clear that she intends to use this opportunity to push her vision of antitrust reform.

"With a new administration, new leadership at the antitrust agencies and Democratic majorities in the Senate and the House, we're well-positioned to make competition policy a priority for the first time in decades," Klobuchar said during a tech conference last month.

Klobuchar's legislation doesn't go as far as the recent report from her counterpart in the house, Rep. David Cicilline. She's not calling for breaking up Facebook or putting an immediate moratorium on all tech mergers. But her reforms would go a long way in fundamentally changing how the tech industry operates.

The legislation would make it harder for powerful firms with substantial market power to acquire smaller companies and forbid mergers that present an "appreciable risk of harming competition." It would force companies like Facebook and Google to prove to government regulators that their mergers would not disrupt the marketplace or increase market concentration.

It would also grant government regulators — namely, the Department of Justice and Federal Trade Commission — new powers and resources to penalize companies acting anti-competitively. It would dole out $484.5 million to DOJ's antitrust division and and $651 million to the FTC. Right now, the agencies are hobbled and limited in how much damage they can do when they find a business is abusing their power. But Klobuchar's legislation would give them significant penalty power, allowing them to bring penalties amounting to up to 15% of the violator's total U.S. revenues or 30% of their U.S. revenues in the affected markets.

Klobuchar's legislation would update the Clayton Act to explicitly prohibit business practices that harm competitors and bar "monopsonies": when there is a market dominated by a single buyer. Experts have argued that the tech industry is made up of a series of monopsonies, pointing to examples like Apple's App Store or Google's search advertising dominance, and antitrust advocates have been pushing for the law to clearly bar this practice.

Klobuchar, who is a moderate, has previously gotten flack from progressive antitrust advocates who say she doesn't go far enough. It's possible they will push her to go further this time around as well.

But the legislation as it stands still has a lot of hurdles to surmount. Democrats hold a slim majority in the Senate and they still need Republican buy-in for large legislative efforts like antitrust reform, which they're unlikely to get. And they're certain to face a blitz of aggressive lobbying from every company that could be affected by the bill, including Big Ag and Big Pharma alongside Big Tech. But she's poised to move forward with support from Cicilline, who was just selected to helm the House's antitrust subcommittee again. And in many ways, their collective efforts are a more serious threat than any Section 230 or privacy legislation on the table right now.

"I'm looking forward to finally having the gavel to be able to mark up bills and send them to the floor," Klobuchar said last month. And she means it.