Rebekah Carmichael, a spokeswoman for the U.S. Attorney's Office, told TPM, "Our office can neither confirm nor deny any specific investigative actions." Sheridan did not immediately respond to a request for comment.
Christie's re-election campaign has also been subpoenaed by a committee in the state legislature that is investigating the closures and other "concerns about abuse of government power." Documents subpoenaed by the state Assembly committee last month indicating Christie's former campaign manager, Bill Stepien, may have been involved in the closures. Christie subsequently asked Stepien to remove his name from the running to be chair of the state Republican Party.
Some Democrats have alleged the closures were ordered by Christie's allies to retaliate against a mayor who declined to endorse him. On Saturday, the mayor of Hoboken, N.J. claimed Christie administration officials threatened to withhold Hurricane Sandy aid from her city unless she approved a real estate project.
Additional reporting by Eric Lach.
This post has been updated.