Many of the 11 candidates who will be at tonight’s prime-time CNN debate (5 p.m. PDT/8 p.m. EDT) see a path to the presidency only by getting out of the long shadow cast by Donald Trump. For that reason, the gathering at the Ronald Reagan Presidential Library figures to be a more combative debate than the first one the Republicans had on Aug. 6 in Cleveland.

"I hear they are going after me. Whatever. Whatever," Trump said at a lively campaign rally in Dallas on Monday.

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This time, Republicans have a greater incentive to raise doubts about Trump since he has built on his lead with four months to go until Iowa holds the first nominating contest on Feb. 1. The latest Reuters-Ipsos opinion poll has Trump leading among Republican voters with 32.2 percent. Retired neurosurgeon Ben Carson was at 15.8 percent, former Florida Governor Jeb Bush at 9 percent and the rest of the field below 6 percent.

Tonight’s debate will be the first time Trump has been on stage with former Hewlett-Packard CEO Carly Fiorina. Trump last week was quoted by Rolling Stone magazine as saying of Fiorina: "Look at that face. Would anyone vote for that?" He later said he was talking about her "persona." 

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In a sign of how fluid the Republican race is, a CBS News/New York Times poll said 63 percent of Republican voters had not yet made a final choice on whom they would support in the race. At the prime-time debate will be Trump, Carson, Bush, Scott Walker, Ted Cruz, Marco Rubio, Mike Huckabee, Rand Paul, John Kasich, Chris Christie and Fiorina.

Rick Santorum, Bobby Jindal, George Pataki and Lindsey Graham will participate in an undercard debate at 3 p.m. PDT/6 p.m. EDT.