Johnson told Reuters there are "still outstanding issues" with the nominee. The panel's top Democrat, Senator Gary Peters, said in an interview there are "bipartisan concerns" related to Vitiello's past tweets and that some rank-and file-agents don't support him.
"I think it will be very difficult for him to get through the committee at this point," Peters added. This is the second time the Senate panel has delayed voting on Vitiello's nomination.
The committee postponed a vote last November after the union, the National ICE Council, first raised concerns about Vitiello's fitness for leading the agency. On Tuesday, union President Chris Crane sent a letter formally asking the panel to oppose Vitiello, saying his prior offensive tweets showed he "lacks the judgment and professionalism to effectively lead a federal agency."
An ICE representative did not have any immediate comment. Vitiello, a former top Customs and Border Protection official, was named ICE acting director in the summer, shortly after Trump ended the controversial policy of separating illegal immigrant children from their parents at the border.
The union's concerns range from allegations of whistleblower retaliation to offensive tweets he posted while serving at Customs and Border Protection. In one social media post, Vitiello suggested the Democratic Party should be renamed as “NeoKlanist,” a reference to the Ku Klux Klan white supremacist organization, and in another Vitiello compared then-candidate Trump to the trouble-making "Dennis the Menace" comic and television character. At the time, Crane said, Vitiello’s Twitter account showed him wearing a Border Patrol uniform.
In his confirmation hearing, Vitiello apologized for the racially tinged tweet and said it was meant as a joke. ICE spokesman Vincent Picard defended Vitiello on Tuesday, saying the Twitter posts were made from a private account while he was off duty, and that the Office of Special Counsel cleared him of any wrongdoing. (Reporting by Sarah N. Lynch; Editing by Chizu Nomiyama and Jeffrey Benkoe)