The conservative website Newsmax will host the debate, scheduled for Dec. 27 in Des Moines. All the GOP contenders have been invited to participate.

Trump announced he would not seek the Republican nomination himself after toying with a bid last spring. The host of "Celebrity Apprentice" has remained visible in the GOP contest, hosting many of the candidates for meetings at Trump Tower in New York City. Former House Speaker Newt Gingrich is set to visit Trump Monday.

He has not yet endorsed a candidate.

Trump has also been a strong critic of President Barack Obama and drew considerable publicity when he questioned the validity of Obama's birth certificate.