SEC Chairman Jay Clayton may get a new ally as the agency considers action related to a controversial Obama-era regulation intended to fight financial industry conflicts of interest.

President Donald Trump is expected to tap Republican think-tank scholar Hester Peirce for a seat on the Securities and Exchange Commission after her nomination stalled in the previous Congress, Bloomberg News reported June 16. She is a fierce critic of the fiduciary rule adopted in 2016 by the Labor Department, which Clayton has asked the public to assess in advance of potential SEC action.

Peirce, a research fellow at George Mason University’s...