Real estate mogul Donald Trump explained his disappointment with Michele Bachmann, who decided not to attend a debate he is moderating.

"You know who I am very disappointed in? Michele Bachmann. She came up to see me four times. She would call me and ask me for advice," Trump said Friday on Fox Business Network.

Trump said that Bachmann suggested if she won the Republican presidential nomination, she would consider him for the vice presidential spot.

"She said if she wins, she would like to think about me for the vice presidency. Most importantly, I did a two-hour phone call for her with her people," Trump continued. "And people said, 'Are you endorsing her?’ The answer was no. And after all that she announced she was not going to do the debate. It’s called loyalty. How do you do that? It’s amazing to me."

On Thursday the Minnesota congresswoman announced she was not attending the Trump-moderated debate. Her announcement meant that all but two Republican presidential candidates — Newt Gingrich and Rick Santorum — had agreed to participate. The debate, hosted by Newsmax, is scheduled for Dec. 27. 

In the same interview Trump suggested he might not moderate the debate if the only participants are Gingrich and Santorum.

"I have to look into it," Trump said.

—This story was updated at 12:23 p.m.