Story highlights Hamilton's departure will be a blow to DHS's policy shop, sources familiar with the situation said

The Justice Department under Sessions has been involved in immigration policy

Washington (CNN) One of the Trump administration's top immigration policy staffers is leaving the Department of Homeland Security to join the attorney general's office at the Department of Justice -- reuniting him with Jeff Sessions.

Gene Hamilton, a senior counselor to the Homeland Security secretary since January and top immigration policy expert for the administration, confirmed the move to CNN.

Hamilton's departure will be a blow to Homeland Security's policy shop, sources familiar with the situation said. The agency is tasked with managing the vast majority of the administration's immigration portfolio.

But the move will reunite Hamilton, a former Sessions staffer, with the Cabinet's strongest immigration policy hardliner, an early supporter of President Donald Trump who has been a key proponent of his aggressive immigration agenda from his perch at DOJ.

Hamilton was a general counsel for Sessions on Capitol Hill and will work directly with the attorney general in his new role. The switch is tentatively expected to begin next week, the sources said.

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