Many people have been left wondering why President Barack Obama has refused to endorse Kamala Harris as the Democratic Party nominee.

According to Biden family sources who spoke with The New York Post, Obama is “upset” that Biden endorsed Harris as the presumptive nominee because he believes she will lose to Donald Trump.

“Obama’s very upset because he knows she can’t win,” the source was quoted as saying. “Obama knows she’s just incompetent — the border czar who never visited the border, saying that all migrants should have health insurance. She cannot navigate the landmines that are ahead of her.”

The source also warned that Harris would likely make a fool of herself at the debate.

“Wait until the debate… She can’t debate,” they continued. “She’s going to put her foot in her mouth about Israel, Palestine, Ukraine. She’s going to say something really stupid.”

The unnamed individual also claimed that George Clooney’s article in The New York Times calling for Joe Biden to pull out of the race was actually orchestrated by Obama in the hope that it would help remove Biden from the race.

Obama also reportedly wants Arizona Senator Mark Kelly to serve as Harris’s running mate.

During his address to the nation on Wednesday evening, Biden praised Harris as both “tough” and “capable” of meeting the challenge in front of her.

“I’d like to thank our great vice president, Kamala Harris,” Biden said. “She’s experienced, she’s tough, she’s capable. She’s been an incredible partner to me and a leader for our country.”