Lina Khan, the antitrust crusader leading the Federal Trade Commission, suffered her first major defeat as Amazon.com Inc. closed its acquisition of movie studio Metro-Goldwyn-Mayer, underscoring the limits to Washington’s efforts to rein in the technology industry’s giants.

Amazon’s victory could be short-lived. The five-member FTC is split 2-2 between Democrats and Republicans, leaving Khan without a Democratic majority to bring cases unless she can muster support from at least one Republican. That will change if the Senate confirms President Joe Biden’s nominee for the fifth seat, Georgetown University law professor Alvaro Bedoya.

“Without three Democrats, Khan is limited with respect to what she can do,” said Bloomberg Intelligence analyst Jennifer Rie. “Once Alvaro Bedoya is confirmed and takes his place as the third Democratic commissioner, Khan will be able to pursue more of her agenda.”

It’s unclear when that could happen, however. Bedoya’s narrow support base among senators has complicated his path to confirmation. Lawmakers have twice deadlocked along party lines. He can still be brought to a Senate floor vote, but under a slower process. Vice President Kamala Harris may have to provide a tie-breaking vote if all Republicans vote against him.

The agency suggested in a statement Thursday that it could still challenge the MGM deal. The commissioners didn’t take a vote to stop the transaction and have authority to file a lawsuit to unwind the deal in the future, though the case would likely face an uphill climb in the courts, according to experts.

In the U.S., companies don’t need affirmative approval from regulators to close deals. Instead, they are free to complete transaction after a specified waiting period unless antitrust enforcers at the FTC or the Justice Department go to court to block a tie-up.

A bill proposed this week by Senator Elizabeth Warren of Massachusetts and Representative Mondaire Jones of New York would overhaul this system by giving the agencies more authority to block deals and prohibiting mergers valued at more than $5 billion, a threshold that would have made the MGM deal illegal.

“Our current antitrust laws don’t give the FTC enough teeth to take down giant mergers like the Amazon-MGM deal,” Warren said in a statement. “My new antitrust bill would not only have made this merger illegal, it would have directed the FTC to review the potential harms to Amazon’s workers and the potential consequences on competition throughout Amazon’s massive ecosystem.”

The bill’s chances of advancing are slim because it doesn’t  have Republican support.

Jones called the deal a “corporate consolidation of power that will undoubtedly hike up prices, lower wages, and lay off even more workers.”

Amazon’s ability to close the deal is a major setback to Khan, who made her name in the antitrust world taking aim at the company’s dominance. In 2017 as a student at Yale Law School, she published a paper arguing that Amazon’s relentless growth posed a threat to competition in digital commerce and how traditional antitrust analysis was failing.

It was a radical position at the time. And it helped establish a movement to overhaul antitrust enforcement in the U.S. to take on corporate giants. Now she’s leading the agency after Biden unexpectedly named her chair.

Since then, Khan has notched two major merger wins: blocking Nvidia Corp.’s acquisition of Arm Ltd. and Lockheed Martin Corps.’s deal for Aerojet Rocketdyne Holdings Inc. Both cases were brought with Republican support. She also resurrected the FTC’s monopoly case against Meta Platforms Inc. that seeks to split off WhatsApp and Instagram.

Amazon is No. 1 in the 2021 Digital Commerce 360 Top 1000. It is No. 3 in the Digital Commerce 360 Online Marketplaces database, which ranks the 100 largest global marketplaces.