Donald Trump. Aaron P. Bernstein/Getty Images Real-estate mogul Donald Trump called the coming Fox News-hosted Republican debate a "total disaster" and shared a Twitter user's post that called Fox News host Megyn Kelly a "bimbo" during a raging series of tweets hours before he was set to boycott the Thursday-night debate.

"The 'debate' tonight will be a total disaster — low ratings with advertisers and advertising rates dropping like a rock. I hate to see this," the Republican presidential front-runner wrote.

The real-estate tycoon had told Fox host Bill O'Reilly on Wednesday night that he hoped Fox did "well," even though he said the network would "make much less" money without him on stage.

A Fox News spokesperson disputed Trump's characterization, telling Business Insider that ad rates have not changed and that no advertisers have backed out of their spots.

"The debate is completely sold out. No rates have changed and there are no advertisers who have backed out. Prices don't change once the orders have been placed," the spokesperson told Business Insider.

CNN's Dylan Byers reported Thursday that ad rates for primary debates and similar events are usually set weeks or months ahead of the event.

Later in the tweetstorm, Trump also continued his assault on Kelly, with whom he has feuded for months.

One tweet, which Trump promoted on his account Thursday morning, attacked Kelly for a GQ Magazine photo shoot and labeled her a "bimbo."

"And this is the bimbo that's asking presidential questions?" the tweet said. The user attached two photos from the shoot with text that read, "Criticizes Trump for objectifying women ... Poses like this in GQ Magazine."

The candidate shared the post a day after he had said he wouldn't refer to Kelly as a "bimbo," a term used to insult women, because doing so would "not be politically correct."

Trump drew some backlash last year when he twice promoted tweets calling Kelly a "bimbo." One of the times Trump retweeted the insult was after Kelly, a moderator at an August debate, confronted him about past comments he had made about women's looks.

He also shared an image that falsely claimed Prince Alwaleed bin Talal of Saudi Arabia had posed with Kelly and was "the co-owner" of Fox News. According to the myth-debunking site Snopes, the photo is fake, and the Saudi prince's investment firm owns a minority share in 21st Century Fox, the parent company of Fox News.

Trump has raged against Kelly and her coverage of his campaign since that August debate. And the Fox host played a key role in Trump's big Tuesday announcement that he would not be attending the debate.

On Wednesday, Trump's campaign announced plans to host a dueling event in Iowa during Thursday's Fox-hosted debate. It said the event would be held to benefit veterans organizations.

Trump refused to back down from his stance Wednesday night, when he appeared on the Fox host O'Reilly's show. On Thursday, he said "two candidates" had contacted him about attending his Iowa event Thursday night.

View part of Trump's tweetstorm below:

This story has been updated with comment from a Fox News spokesperson.