Donald Trump and Ben Carson say they do not like the format of CNBC’s upcoming debate. (Photos: Darren McCollester/Getty Images, Chip Somodevilla/Getty Images)

Donald Trump and Ben Carson are threatening to boycott the next Republican presidential debate if the event’s hosts do not cave to their demands.

The candidates want CNBC and the Republican National Committee to shorten the Oct. 28 debate in Boulder, Colo., so it does not exceed 120 minutes. They also insist that it must include opening and closing statements from all of the candidates.

In a letter to CNBC Washington bureau chief Matthew Cuddy, obtained exclusively by NBC News, Trump and Carson protested the debate agenda shared with their campaigns and reiterated their concerns on a phone call: over-long debate time plus four commercial breaks, as well as an absence of opening and closing statements.

Trump and Carson threaten to opt out of CNBC debate by Alexandra Jaffe

“Neither of those conditions are acceptable,” the letter reads. “Neither Mr. Trump or Dr. Carson will participate in your debate if it is longer than 120 minutes including commercials and does not include opening and closing statements.”

Trump, the GOP frontrunner, has attracted an unprecedented level of attention for the party’s primary since declaring his candidacy this summer, almost single-handedly turning the first two debates into ratings behemoths. To put it bluntly, Trump equals greater viewership — something CNBC surely wants.

Carson, too, has garnered a considerable amount of attention. The retired neurosurgeon became one of the party’s breakout stars when he surged in the polls late this past summer.

As expected, Trump did not rest after sending the letter. The billionaire businessman, who is no stranger to online feuds, took to Twitter to criticize CNBC for its plans.

The @GOP should not agree to the ridiculous debate terms that @CNBC is asking unless there is a major benefit to the party. — Donald J. Trump (@realDonaldTrump) October 15, 2015

.@CNBC is pushing the @GOP around by asking for extra time (and no criteria) in order to sell more commercials. — Donald J. Trump (@realDonaldTrump) October 15, 2015