Thomas Homan, the Trump administration’s top immigration enforcement official, announced Monday that he plans to step down from his job, less than six months after Trump nominated him to be director of U.S. Immigration and Customs Enforcement.

Homan was named ICE’s acting director soon after Trump took office in 2017, and the tough-talking, barrel-chested former Border Patrol agent quickly became an unapologetic enthusiast for the administration’s more aggressive enforcement approach.

Under Homan, immigration arrests surged 40 percent after agents scrapped an Obama administration policy of targeting serious or violent criminal offenders in favor of casting a wider net. Homan said those living illegally in the United States “should be afraid” that his agents could be coming for them.

Pleased with Homan’s beat-cop demeanor, Trump picked him for the permanent ICE leadership role in November. But his nomination went nowhere and never reached a vote on the Senate floor.

Homan ran ICE in a provisional capacity for so long the agency could no longer legally refer to him as its “acting director,” instead identifying him as its “Senior Official Performing the Duties of the Director.”

In recent months, Homan told friends and co-workers that he felt increasingly sidelined by his boss, Homeland Security Secretary Kirstjen Nielsen, according to three people close to Homan. When Nielsen met with lawmakers this year to negotiate an immigration deal, Homan was not invited to join the discussions, and his frustrations deepened.

Homan informed Nielsen in early February of his plans to retire, but she urged him to delay the announcement because there was already so much turnover at the highest levels of the Trump administration, a person with knowledge of their talks said.

Homan’s retirement plans were first reported by the Wall Street Journal.

In a statement Monday, Homan said the decision was prompted by a desire to spend more time with his family.

“It has been the honor of my life to lead the men and women of ICE for more than a year,” his statement read. “The decision to leave federal service after more than 34 years is bittersweet, but my family has sacrificed a lot in order for me to serve and it’s time for me to focus on them.”

Nielsen informed DHS staff of Homan’s retirement in a memo, calling him a “patriot and true public servant.”

“Under his exceptional leadership, the men and women of ICE have made significant progress in restoring the rule of law to our immigration system,” Nielsen wrote. “He has made my predecessors and myself better secretaries, faithfully upholding the Constitution and executing ICE’s law enforcement mission.”

Homan had been the subject of several critical reports in recent weeks regarding ICE policies that include the forced separation of immigrant families in detention as well as the agency’s controversial arrest practices.

Homan’s statement said his agency has been repeatedly maligned by “unfair and false criticism from politicians and the media.”

In a letter Friday, nearly 20 Senate Democrats asked the Department of Homeland Security to provide documents explaining why Homan’s nomination had stalled, suggesting DHS didn’t want him to face scrutiny.

“We understand that the Trump Administration may be concerned about Mr. Homan answering questions under oath about his leadership of ICE, as well as the possibility that Mr. Homan’s nomination could be defeated in the Senate,” the letter said. “However, the Senate is an independent branch of government and has a responsibility under the Constitution to provide its advice and consent on this nomination.”

Homan was to announce his retirement Monday night at an award ceremony where he was to receive a leadership award from the Federal Law Enforcement Officers Association Foundation, his statement said.