What the 2016 presidential candidates are saying on the trail and on social media today:
By late afternoon Wednesday, Trump had not yet formalized the competing event he promised, one that would raise money for veterans.
Ted Cruz's campaign has started selling "Make Trump debate again" hats on its website, a play on Trump's slogan, "Make America great again," and the popularity of Trump campaign hats. CBS News' Alan He reports they're on sale for $25, but they won't start shipping until after Feb. 10, just after the New Hampshire primary.
Ben Carson was asked about Trump's decision not to debate during an interview with Wolf Blitzer on CNN. "I'm not sure that it matters that much because it's not really about me or Donald Trump or Ted Cruz or any of the candidates," Carson said. "It's about the American people."
At a town hall in Des Moines, Jeb Bush seemed dubious that the GOP front-runner would really sit out the debate.
"[Trump] apparently is not going to come to the debate -- although I got a $20 dollar bet he'll show up -- because he thinks he's not being treated fairly," Bush said, in response to a question at a campaign event. "Really? Donald Trump's not being treated fairly by the press? He consumes all the press. It's like, he's a Stradivarius violinist from the Vienna symphony, man. The press is just being played like nobody's business."
John Kasich, in an interview with Fox News' Sean Hannity, considered the possibility of a weak finish in New Hampshire, where he has staked his candidacy.
"If I don't break out?" Kasich mused. "I probably will cry for little while."
Hannity responded, "That's the best answer I've ever gotten."
CBS News' Sopan Deb, Alan He and Alexander Romano contributed to this compilation.