Steve Peoples ?and Jill Colvin

DES MOINES, Iowa: An explosive feud between Donald Trump and Fox News Channel is overshadowing the final sprint to Iowa’s presidential caucuses, injecting a new sense of chaos into the 2016 Republican contest.

On the eve of the final debate before Iowa voters weigh in, Trump refused to back off his decision to boycott Thursday’s prime-time faceoff. His campaign insisted that debate host Fox News crossed a line with a sarcastic statement mocking him and continued to criticize moderator Megyn Kelly. In turn, Fox accused Trump’s camp of trying to terrorize its employees.

“They think they can toy with Mr. Trump,” campaign manager Corey Lewandowski said Wednesday on MSNBC’s Morning Joe. “Mr. Trump doesn’t play games.”

Trump reiterated his plans to skip the debate in an interview Wednesday on Fox News, saying, “I just don’t like being used.”

As the public clash intensified, Trump’s Republican competitors hunkered down for a day of private debate preparations filled with uncertainty. Skeptical that he would follow through on his boycott, the other campaigns held practice sessions with and without someone playing Trump.

Some thought the absence of Trump could make another leading Iowa contender, Texas Sen. Ted Cruz, a prime target for campaigns eager to spark a last-minute shakeup. Cruz challenged Trump to a separate one-on-one debate, a proposal that was dismissed by his opponent.

“Even though I beat him in the first six debates, especially the last one, Ted Cruz wants to debate me again. Can we do it in Canada?” Trump tweeted, referencing Cruz’s birthplace.

Cruz renewed the invitation to debate, saying they could meet Saturday in Sioux City, Iowa.

“It’s not really that Donald is afraid of me,” Cruz said at a rally Wednesday night outside of Des Moines. “He’s afraid of you. He doesn’t want to answer questions from the men and women of Iowa about how his record doesn’t match what he’s selling.”

Some foes saw the shakeup as an opening to rise above the ruckus.

“These kinds of theatrics by Ted Cruz and Donald Trump are an entertaining sideshow, but they have nothing to do with defeating Hillary Clinton,” Florida Sen. Marco Rubio said. “We don’t have time for these kinds of distractions.”

Instead of debating Thursday night, Trump will host what his campaign is calling a “special event to benefit veterans’ organizations.” The campaign on Wednesday evening formally announced details for the event, scheduled to begin at the same time as the debate — and just two miles away.