Trump administration officials have ordered the F. B. I. to revisit a decade-old counterintelligence investigation into Representative Eric Swalwell, a prominent California Democrat and Trump critic, according to sources familiar with the matter.

The move, made at the Trump White House's behest, has alarmed career law enforcement officials who fear the extensive files could be leaked publicly to damage Swalwell's political standing. The probe dates back to 2012, when the F. B.

I. investigated Chinese national Christine Fang for alleged ties to Chinese intelligence while Swalwell was a city council member in Dublin, California. The F. B.

I. concluded the investigation without charges, and the Justice Department has a policy against releasing derogatory information about individuals not charged with crimes. However, the Trump administration's directive has bypassed normal procedures, instructing agents to gather and review the files ahead of a potential weekend deadline. Supervisors were told to lightly redact records and share them with senior administration officials in Washington.

Swalwell, now running for California governor, has denied any wrongdoing and called the action a political vendetta, noting he severed ties with Fang in 2015 after a F. B. I. briefing.

The episode echoes broader Trump administration tactics targeting political opponents, including failed criminal cases against figures like New York's attorney general. The F. B.

I. and Justice Department declined immediate comment.