Sec. Sean Duffy, Sen. Thom Tillis

Transportation Secretary Sean Duffy joins "This Week" for an exclusive interview about the ongoing DHS shutdown and air travel chaos. Sen. Thom Tillis, R-N.C., sits down with ABC News' Jonathan Karl to discuss the Iran war, the Trump administration and more. Roundtable: Former New Jersey Governor Chris Christie, former DNC Chair Donna Brazile, "Washington Post" congressional reporter Marianna Sotomayor, and SCOTUSBlog editor, Sarah Isgur, author of the upcoming book, "The Last Branch Standing".