U.S. Republican presidential hopeful Donald Trump on Tuesday abruptly withdrew from a debate with party rivals this week out of anger at host Fox News, leaving the last encounter before Iowa's first-in-the-nation nominating contest without the front-runner.

Trump's campaign manager, Corey Lewandowski, told reporters after a combative news conference held by the candidate that Trump would definitely not be participating in the debate scheduled for Thursday.

During the news conference before he addressed a large crowd in Marshalltown, Iowa, Trump expressed irritation that Fox News planned to leave in place as a moderator the anchor Megyn Kelly, whose questioning of Trump at a debate last August angered him.