Independent presidential candidate Evan McMullin told Business Insider Donald Trump’s campaign staffers have told him that the GOP nominee has times where he “hides in his apartment” and they’re growing “frustrated.”

McMullin also said that it’s “unclear” whether Trump “will make it through this campaign.”

He continued: “I’m hearing from people inside his campaign that there are times now when he hides in his apartment and doesn’t meet with any people. When he campaigns he goes out to a place he has to fly back home to New York. This is a fragile man and a fragile campaign and I’m not quite sure what’s going to happen in the days and weeks ahead of him. I’m not sure the RNC can continue to support him given his weakness as a man and as a politician and as a candidate for the presidency.