Attorney General Jeff Sessions went to the mat recently against pro-China officials within the Trump administration to prevent the forcible return of a dissident businessman to China.

According to a person familiar with the issue, Mr. Sessions told administration officials during a meeting this spring that he would resign before agreeing to send back Chinese businessman Guo Wengui, who Beijing says is wanted on corruption charges but who has become a major political thorn in the side of the Chinese Communist Party leadership.

Mr. Sessions made the resignation threat in the face of pressure from officials at the White House and State Department, who themselves have been the targets of an intense influence operation by China seeking the return of Mr. Guo, a real estate mogul who in January began revealing secrets on YouTube, Twitter and Facebook about what he says is widespread corruption among Chinese leaders.