Author Eleanor Clift on Sunday warned former Republican strategist Steve Schmidt about promoting a "spoiler" candidate who could help President Donald Trump get re-elected in 2020.

During a panel discussion on MSNBC about third-party candidates, host Kendis Gibson noted that former Starbucks CEO Howard Schultz is considering an independent bid for president in 2020.

"Is he a formidable candidate if he runs?" the MSNBC host asked Clift.

"I don't think so," Clift replied. "Michael Bloomberg had a lot of money and a lot of campaign caché and he looked at running as an independent in a couple of election cycles. And the data was always presented to him that showed he would be a spoiler, he couldn't win."

"And the danger is, you're going to elect the candidate you least want to elect," she cautioned.

Clift then took a moment to say that she is "amazed" to see Schmidt, a former aide to John McCain's 2008 campaign, advising Schultz.

"Steve Schmidt has been advising Howard Schultz," she explained. "Steve Schmidt has spent the last two years kind of apologizing for his role in getting Sarah Palin on the ticket with John McCain."

"I think he'd think long and hard about being part of a another effort that could well turn out not like wants it to," she concluded.