Rep. Michael McCaul, R-Texas, has emerged as the immigration hawks' least favorite possible pick for running the Department of Homeland Security.

Skeptics include activists and commentators who endorsed President-elect Trump mainly on the issue of immigration control. These conservatives applauded the nomination of Sen. Jeff Sessions, R-Ala., for attorney general but have been worried about the homeland security position.

"If Rep. McCaul is chosen to head DHS, he will need to take a much more expansive view of border and immigration enforcement than he has in the past," said Federation of American Immigration Reform president Dan Stein in a statement provided to the Washington Examiner. Stein's group, which favors tougher enforcement and lower immigration levels, reacted coolly to McCaul speculation.

The Department of Homeland Security is the most important agency for immigration enforcement, and critics regard McCaul as too lax in this area. He was one of just 19 House Republicans who signed on to then-Speaker John Boehner's immigration principles, which hardliners regarded as supporting amnesty for illegal immigrants.

McCaul chairs the House Homeland Security Committee but has co-sponsored legislation many immigration hawks felt diluted border fencing and exit-entry systems contained in other laws. His Secure Border Act of 2015 was criticized for not going far enough and did not pass. McCaul's C-plus lifetime grade from the restrictionist group Numbers USA puts him in the bottom fifth among House Republicans.

The Texas congressman wasn't helped when he was praised by President Obama's Homeland Security Secretary Jeh Johnson. "On his behalf, I don't know anybody who is stronger on border security in Congress that I have dealt with," he told the Washington Times, a comment that is likely to be used against him in the future.

Earlier in the week, the Federation of Immigration Reform released a "blueprint" for the transition team to follow on immigration, including the repeal of all of Obama's executive orders deferring enforcement action against illegal immigrants, mandatory E-Verify, no legalization programs and an end to birthright citizenship.

Much of this is already part of the Trump immigration agenda. Immigration hawks believe that for their preferred policies to be implemented, they will need the strongest possible appointees from their perspective at Homeland Security, Justice and the Department of Labor.

Many immigration hardliners prefer Kansas Secretary of State Kris Kobach, who has helped formulate tough state laws designed to curb illegal immigration, for the Department of Homeland Security. Trump has also interviewed Milwaukee County Sheriff David Clarke. Clarke and Kobach would likely be much harder to confirm than McCaul, who is popular on Capitol Hill.

McCaul has also been talked about as a possible primary challenger for Sen. Ted Cruz, R-Texas, in 2018. Cruz spoke favorably about Trump interviewing McCaul for a Cabinet position.

The pushback against McCaul comes as immigration hawks who supported Trump have been publicly skittish about the president-elect's commitment to follow through on the issue. "Sounds like the big sell-out is coming," columnist Ann Coulter tweeted in response to news that Vice President-elect Mike Pence and House Speaker Paul Ryan were "going straight to work" on immigration.

Coulter's book In Trump We Trust made the case for the incoming president largely on the basis of immigration. Her previous book, Adios, America!, has been credited with stiffening Trump's immigration position. She has been critical of both Ryan and Pence on the issue, supporting the former's unsuccessful immigration hawk primary challenger.

Trump's own immigration rhetoric has been inconsistent. He has formally adopted restrictionist positions and defended them in a late August speech, reportedly written by Stephen Bannon and former top Sessions aide Stephen Miller. But he vacillated on defending some of his harder-line stances during the primary debates and has hinted to less hawkish audiences, like the New York Times and his own Hispanic advisory council, that they would find much to like in his immigration policy.

The Department of Homeland Security position remains open. Trump has said that most of the Cabinet positions will be filled next week.