WASHINGTON — President-elect Joseph R. Biden Jr. is expected to select Katherine Tai, the chief trade lawyer for the House Ways and Means Committee, as the United States trade representative, a key post that will bear responsibility for enforcing America’s trade rules and negotiating new trading terms with China and other countries, according to people familiar with the plans.

Ms. Tai has garnered strong support from colleagues in Congress, who credit her with helping to wrangle an unruly collection of politicians and interest groups in negotiations to pass the revised North American Free Trade Agreement. From 2007 to 2014, Ms. Tai worked for the Office of the United States Trade Representative, where she successfully prosecuted several cases on Chinese trade practices at the World Trade Organization.

If confirmed, Ms. Tai, who is Asian-American, would be the first woman of color to serve as the U.S. trade representative, a cabinet-level official who carries the rank of ambassador.

Ms. Tai’s selection was earlier reported by Politico and The Wall Street Journal.

Although Mr. Biden has said he does not intend to begin negotiating new free-trade agreements until he has made “major investments here at home and in our workers,” his trade representative will still have plenty to do. Those tasks are likely to include ensuring that American trade rules are adequately enforced and that they promote rather than impede other parts of Mr. Biden’s agenda, including fighting climate change and encouraging domestic investment, for example through augmenting Buy American programs.

Congressional Democrats have fought for Ms. Tai to be appointed in part because they believe she would play a vital role in making sure that the terms of the United States-Mexico-Canada Agreement, which replaced NAFTA this year, are enforced. That includes bringing new trade cases against Mexican factories that violate labor rules, and ensuring that Mexico will follow through with ambitious reforms to its labor system.

As chief counsel for the Ways and Means Committee, Ms. Tai played a key role in crafting the Democratic demands for final changes to U.S.M.C.A., which was negotiated by the Trump administration. In that capacity, she balanced the competing demands of labor unions, environmental groups, corporate lobbyists and the administration, and helped to hammer out a deal that passed both houses of Congress by a wide margin.

In a November letter to Mr. Biden, 10 female House Democrats wrote that Ms. Tai’s central role in that negotiation “makes her uniquely qualified to lead implementation and enforcement efforts” as the next trade representative.

“Ms. Tai knows every tool available to hold Mexico and Canada accountable,” the lawmakers wrote.

Though sometimes a lower-profile position, the post of trade representative has taken on greater importance under President Trump, who has used the office to impose substantial tariffs against foreign countries and negotiate a series of trade deals, both small and large.

Mr. Biden’s top trade negotiator will be responsible for dealing with much of that legacy, including helping to decide whether to continue levying tariffs on Chinese goods, and whether to continue granting certain companies exclusions from those tariffs. Many of those exclusions are set to expire on Dec. 31, and it remains unclear whether Mr. Trump plans to extend them.

The new trade representative will also be responsible for reshaping the office to fit Democratic priorities, like increasing protections for workers, mitigating climate change and raising standards for consumer protections. Mr. Biden’s pick will also be responsible for rebuilding trading relations that have been strained by Mr. Trump’s aggressive approach, including with Europe, Canada, Japan and Mexico.

Supporters say Ms. Tai is also uniquely positioned to address economic challenges from China, regarded as America’s biggest source of competition in the trade sphere.

In addition to litigating trade disputes against China at the World Trade Organization over issues including subsidies and export restraints, Ms. Tai worked on China-related issues during her time in the House, including strategies to reshore American supply chains and legislation to bar imports made with forced labor from Uighurs and other minorities in China.

Ms. Tai has a background in China, having served as a teaching fellow there in the late 1990s and speaking fluent Mandarin Chinese.

In the House, she also led an effort to look at the legacy of racial injustice in U.S. trade policy, and how gains from trade could be made more inclusive.

Thomas Kaplan and Emily Cochrane contributed reporting.