Tonight's Debate Could Change the Race

It's been a while, but America's favorite political game show is back. Yes, the Republican presidential candidates will square off in Mesa tonight for their first debate in nearly a month. Here are the storylines in play:

• The final showdown—The stakes are "about as high as they could be," the Washington Post observes, because this might be the last debate of the GOP primary, and certainly the last before Super Tuesday. And since losses in Arizona and Michigan could be fatal for Mitt Romney's campaign, he has to perform tonight.

• Rick Santorum on the hot seat—This will be Santorum's first debate as what Politico calls the "de facto frontrunner," meaning he's going to take heat, particularly from Romney. But Santorum has actually proven to be pretty good at counterattacks, and his team is confident—one adviser mocks Romney as easy prey because he sticks to "Pavlovian" responses.
• Ron Paul, Romney pal—Paul has developed a friendship with Romney and, given that he's never used debates as his major platform, he's likely to have his back in the face of attacks.
• Newt Gingrich: Mr. Nice Guy?—"Ironically, Newt is in a position to look less negative than Romney or Santorum," one campaign source says, because those two will be beating up on each other. "Newt can rise above it and seem statesmanlike."
• John King's revenge—Newt Gingrich left moderator John King with serious egg on his face during the Jan. 19 debate. "I would be surprised if John were not more aggressive," one Republican pollster tells the Arizona Republic.

(More Republican debate stories.)