The former acting director of Immigration and Customs Enforcement (ICE), Thomas Homan, told Fox News on Sunday that President Trump made the right move replacing Homeland Security Secretary Kirstjen Nielsen with U.S. Customs and Border Protection Commissioner Kevin McAleenan.

Homan, a Fox News contributor, called McAleenan one of the smartest men with whom he has worked.

“He knows border issues, and he can hit the ground running,” Homan told Jon Scott on “Fox Report.” “He knows the border... he will start day one.”

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Nielsen resigned on Sunday amid the administration’s growing frustration over migrants approaching the Mexico border.

Trump thanked her for her work in a tweet and announced McAleenan would be taking over as acting head of the department. McAleenan is a longtime border official who is well-respected by members of Congress and within the administration. The decision to name an immigration officer to the post reflects Trump’s priority for a sprawling department founded to combat terrorism following the Sept. 11 attacks.

Homan said he blamed Congress and current U.S. law for the border crisis: “We are enticing people to come.”

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However, he noted that McAleenan was the kind of man who could tackle the new wave of migration, which has taxed resources along the border.

“He will think outside the box,” Homan said. “Kevin will put his foot on the gas.”

Fox News' Jon Scott and The Associated Press contributed to this report.