Debate's Big Question: Will Anyone Go After Trump? What to watch for in Tuesday night's Republican contest By John Johnson, Newser Staff Posted Dec 15, 2015 6:54 AM CST 53 comments Comments Donald Trump speaks at a rally Monday in Las Vegas. (AP Photo/John Locher) (Newser) – Tuesday night brings the last debate of the year for Republicans, and one common theme in previews is that in a year of relatively lively debates, this one might be the liveliest yet. Some things to watch: Will anyone hit Trump? "Easily the biggest question" of the night is who, if anyone, will go after Donald Trump in "a long-awaited have-you-no-decency-sir moment," says Politico. Ted Cruz and Marco Rubio will likely pass, but keep an eye on Chris Christie or perhaps Jeb Bush or Carly Fiorina. But which Trump? CNN notes that Trump has been content in some debates to "fade into the background," but he also knows that millions will be tuning in to watch him defend his plan to keep Muslims out of the country. Does he "play it safe and lock in his front-runner status?" Cruz vs. Rubio: Now that he's near the top of the polls, Cruz is "likely to come under sharp attack," says the New York Times. Look for Rubio in particular to go after him on immigration and national security, particularly over Cruz's support of guest-worker visas and curbing domestic surveillance. Rubio himself, though, is vulnerable over his 2013 work on providing immigrants a path to citizenship, a topic that has yet to surface in the debates. Christie emerging: One of Slate's key questions is: "What Will Chris Christie Do?" He's rising in the polls, especially in New Hampshire, and given Bush's lackluster debate performances, the New Jersey governor is the "establishment man best suited to try to shake things up." Scary times: A big topic is expected to be foreign policy and the fight against ISIS because of the attacks on Paris and San Bernardino, notes Time: "The more serious tone will likely reward candidates who adapt their messages to fit the new dynamic of the race, and may pose a problem for those who struggle on the substance." Details: The main debate airs at 8:30 Eastern on CNN. The undercard (Mike Huckabee, Lindsey Graham, George Pataki, and Rick Santorum) begins at 6.