Thursday night’s Republican presidential debate will be the sixth of the primary campaign, but only the next to last before the Iowa caucuses. Face-offs held in the final weeks and days before the nominating contests tend to matter more. And the attacks tend to get rougher.
  1. Trump vs. Cruz
    Donald Trump has slowly but ingeniously generated and encouraged questions about Sen. Ted Cruz’s eligibility to be president of the United States. But he told CNN that he had no plans to bring up whether Cruz is a “natural-born citizen" at the debate. It remains to be seen whether Cruz will forcefully assail Mr. Trump’s command of foreign affairs, his “New York values” or anything else about him in a nationally televised debate.
  2. Christie vs. Rubio
    For weeks, Gov. Chris Christie seemed to be having a resurgence in New Hampshire. Then an outside group supporting Sen. Marco Rubio aimed a blistering attack ad at him there. Christie responded viscerally, saying that Rubio was too weak and ineffective to take on Hillary Clinton and suggesting that she would “cut his heart out” in a general election debate.
  3. Cruz v. Rubio
    Rubio also strayed into a minefield with Cruz after trying to deflect criticism of his own record on immigration by suggesting that the two shared the same positions on it. Cruz has retaliated by pointing repeatedly to Rubio’s work with Sen. Chuck Schumer, who is loathed by conservatives, on a failed effort to overhaul the nation’s immigration laws, which conservatives loathed even more.
  4. Bush vs. Trump, or Someone Else?
    In recent weeks, Jeb Bush has emerged as Trump’s chief critic, portraying himself as the only contender gutsy enough to stand up to him. But Trump is not Bush’s most immediate concern. The “super PAC” supporting Bush has been firing away with direct mail pieces at Christie and bludgeoning Rubio in television ads. Bush is vying for support from right-of-center voters who are turned off by Trump and Cruz. He badly needs a breakthrough debate moment.
  5. Trump vs. Himself
    In the previous debates, Trump has been flanked by a wide array of rivals on either side. At times, he seemed content to disappear while others onstage addressed the intricacies of policy. But in South Carolina, just 7 candidates will participate in the main event. That means more microphone time for Trump, but less opportunity to hide.