Former Massachusetts Gov. Mitt Romney says he will not participate in this month's GOP presidential debate hosted by real estate mogul Donald Trump due to a packed schedule.

In addition to campaigning in Iowa, Romney explained he already had two debates scheduled for December.

"I spoke with Donald Trump earlier today and indicated that we just can't make this debate," Romney told Fox News' "Your World With Neil Cavuto," adding that he was just too busy. 

"He understood my perspective and wished me well," Romney added.
    
Jon Huntsman and Rep. Ron Paul of Texas also declined to take part in the debate. They said the event would be media circus and a distraction from important issues.

Former House Speaker Newt Gingrich and Rick Santorum have committed to participate.