An article filled with quotes from McAleenan on October 1 in the Washington Post made clear his time at DHS might be short, as he was described as isolated inside the Trump Administration.
"What I don't have control over is the tone, the message, the public face and approach of the department in an increasingly polarized time," McAleenan said in the Post article.
Democrats said the change after six months was evidence of a Department under stress - filled with 'acting' officials.
"This is the 4th DHS Secretary to leave the Trump Admin," tweeted Rep. Zoe Lofgren (D-CA), as Democrats have bitterly fought the President's policies on illegal immigration.
"I am not here to defend Kevin Mcalleenan," tweeted Sen. Brian Schatz (D-HI). "But I will tell you that it is likely to get worse without him."
“The departure of the Acting Homeland Security Secretary is the latest sign of this Administration’s failed leadership, which has worsened the humanitarian situation at the border, injected pain and tragedy into countless lives and done nothing to improve the situation at the border,” said House Speaker Nancy Pelosi.