Republican presidential candidates appear during the CNN Republican presidential debate at the Ronald Reagan Presidential Library and Museum on Wednesday, Sept. 16, 2015, in Simi Valley, Calif.

(AP Photo/Chris Carlson)

Just a day after Republican presidential hopefuls, including frontrunner Donald Trump, threatened to pull out of the Oct. 28 debate in Boulder, CNBC changed terms of the event to keep the candidates happy.

CNN reports that the debate will be limited to two hours and will allow opening and/or closing statements. 

"They said those conditions are 'all but certain'," as they still needed all the campaigns to sign off on the new format, a source with one of the campaigns told CNN.

Trump called the change "fantastic."