A former Williams & Connolly partner in Washington who has served as a top U.S. trade official since early last year will be the Trump administration's nominee for legal adviser at the U.S. State Department, a key position central to the formulation of U.S. foreign policy and one that would have a central role as tensions mount with Iran.

The nominee, Curtis J. Mahoney, would succeed Jennifer Newstead as the Senate-confirmed leader of the State Department's legal team. Newstead, a former partner at Davis Polk & Wardwell, was hired last year as the general counsel to Facebook. The White House announced its nomination plan on Friday.

Marik String has served as acting legal adviser since May 2019. String, formerly an associate at Wilmer Cutler Pickering Hale and Dorr, first joined the State Department as a senior adviser in July 2017.

Mahoney, who goes by C.J., first joined the Trump administration in March 2018 as deputy U.S. Trade Representative for investment, services, labor, environment, Africa, China and the Western Hemisphere. He joined Williams & Connolly in 2008 and was promoted to partner 2015. In private practice, Mahoney specialized in international disputes and arbitration, and his clients included 21st Century Fox, News Corp., Merck & Co., Samsung Electronics America Inc. and the Carlyle Group.

Mahoney's nomination arrives amid significant rising tension involving Iran, after the U.S. conducted a military strike killing the country's top military commander. Iranian leaders have called the U.S. move a "terrorist action" and vowed retribution.

Separately, Mahoney would step into a State Department mired in intense scrutiny over the Ukraine affair. Mike Pompeo, the secretary of state, was reportedly in the loop on the Trump administration's efforts to pressure Ukraine to investigate Trump's political rivals in the United States. Trump's squeeze on Ukraine, by withholding military aid as part of his push to get a "favor," is central to one of two articles of impeachment the House approved last month.

Mahoney, who clerked for then-Justice Anthony Kennedy during the 2007-2008 term, is among a small group of former Williams & Connolly lawyers who took positions in the Trump administration or landed on the federal bench.

Allison Rushing, one of the youngest-ever federal appeals nominees, was confirmed last year to a seat on the U.S. Court of Appeals for the Fourth Circuit. Former partner Thomas Ward, who joined the Justice Department in 2017, is reportedly under consideration for enforcement director at the Consumer Financial Protection Bureau. Emmet Flood, who served as a special counsel advising Trump during the Mueller investigation, returned to Williams & Connolly in October.

Harold Koh, a former Obama-era legal adviser at State, teaches international law at Yale Law School. John Bellinger III, who served as legal adviser during the George W. Bush administration, is a partner at Arnold & Porter Kaye Scholer.