Donald Trump has said he will boycott the final Republicanpresidential debate before the Iowa caucuses.
The maverick Republican frontrunner accused Fox News debate moderator Megyn Kelly, whom he has clashed with in the past, of being a "lightweight".
The unexpected move prompted his closest rival, Senator Ted Cruz, to challenge him to a one-on-one debate.
Mr Trump's campaign manager announced the decision on Tuesday evening, with just 48 hours to go before the debate.
"He will not be participating in the Fox News debate Thursday," Corey Lewandowski said immediately after the press conference.