President Trump's outgoing antitrust chief Makan Delrahim on Tuesday endorsed a proposal from House Democrats that would put new limits on acquisitions by large companies, during comments made at a Duke University event.

Why it matters: Momentum is building for major antitrust reform, updating rules that were written for railroads instead of routers.

• Democrats began agitating for it shortly after Trump took office. Some Republicans view it as a way to curb Big Tech's power. And Delrahim's words may help sway others GOP members who are on the fence.

The draft legislation cited by Delrahim would presume horizontal acquisitions by a company with more than a 50% market share in a defined market are anticompetitive, no matter the size of the acquired company.

• Delrahim said: "The goal here is to create a bright-line rule for merging parties and for courts, allowing for better business planning by private parties and better litigation planning by federal antitrust enforcers."
• He added that his endorsement was grounded in DOJ's experience with both the Visa/Plaid and Sabre/Farelogix situations.
• Delrahim also proposed the creation of a public-private rulemaking body to focus on increasing competition among online platforms. Plus a pilot “specialized antitrust court,” to see if it could perform better than courts with generalist judges who lack deep antitrust and/or industry knowledge.

The bottom line: Washington, D.C. changes today, with a new President and a new Senate majority. But the evolution of antitrust law continues to point in the same direction.

Go deeper:Read Delrahim's full speech