The House Oversight and Government Reform Committee has opened an investigation into leaks that scuttled immigration arrests earlier this year.

Rep. Clay Higgins, Louisiana Republican, said the leaks came from actors within the administration, and he wants to figure out who they are and how they can be stopped.

“This is a catastrophic breach of federal immigration enforcement operations that jeopardizes the safety and security of every American,” Mr. Higgins said. “My first investigation as chairman of the subcommittee on Federal Law Enforcement will seek to hold these deep state leakers accountable.”

Some high-profile Trump team figures speculated that the FBI was the weak link.

Mr. Higgins asked for briefings from the FBI director and the heads of the Drug Enforcement Administration, the Bureau of Alcohol, Tobacco, Firearms and Explosives, and U.S. Immigration and Customs Enforcement.

“The leaked plans tipped off dangerous criminals about imminent law enforcement actions, enabling them to evade apprehension and perpetuate the threat they pose to national security and the American public,” the chairman said in letters asking for the agencies’ cooperation with his investigation.

In one instance, word was leaked of an impending ICE swoop through the Denver area to target members of Tren de Aragua, the Venezuelan gang.

Activists used bullhorns to warn migrants of the arrests. Federal agents found some of their target locations empty when they arrived.

The Los Angeles Times reported that impending arrests in California were also leaked ahead of time.

Homeland Security Secretary Kristi Noem boldly declared the FBI responsible.

“The FBI is so corrupt,” she posted on social media.

The FBI denied responsibility and called Ms. Noem’s speculation “unfounded” and “deeply irresponsible.”

The finger-pointing over arrests reflects how much is riding on the numbers.

Despite success in closing the border to illegal immigration, Mr. Trump’s team has struggled to meet his expectations for mass deportations.

ICE data shows the agency is averaging about 645 deportations daily, a decrease from the early days of the Trump administration and down 17% from last year under President Biden.

ICE did record nearly 44,000 people in detention as of late last month. That was the highest rate since 2019, when Mr. Trump was dealing with a border surge.

The FBI became involved in immigration enforcement because Ms. Noem deputized the bureau and other Justice Department law enforcement agencies to help ICE make arrests in the U.S. interior. These agencies include the DEA, ATF, the U.S. Marshals Service and the Bureau of Prisons.

They are helping ICE when it has to go into communities to make arrests, which usually requires teams of officers.

The Washington Times reported that some FBI agents begged off or failed to show up when they were called to help on an immigration operation in Chicago.

White House border czar Tom Homan, a former head of ICE, said Tuesday on Fox News that the administration knew the source of the leak from the arrests in Aurora, Colorado.

In a separate interview with Fox News’ Sean Hannity, Ms. Noem said she had identified “some leakers” in her department, though she didn’t specify the leaks.

“They will be fired,” she said.