Billionaire former Starbucks chief executive Howard Schultz doesn't have the guts to run for president, U.S. President Donald Trump said on Monday.

Schultz, who has never before run for political office, told broadcaster CBS that he has "a long history of recognizing that I'm not the smartest person in the room." If he were president, he would "have to recruit and attract people who are smarter than me and more experienced," he said.

Trump pounced on Schultz's comment about his intelligence, writing on Twitter that Schultz "doesn't have the 'guts' ... I agree with him that he is not the 'smartest person.' Besides, America already has that!"

Trump said he watched Schultz, a businessman who grew Starbucks into an international coffee retailer, in the Sunday evening broadcast on "60 Minutes." He said he also hoped Starbucks "is still paying me their rent in Trump Tower!"

"I am seriously thinking of running for president," Schultz told the CBS news show "60 Minutes" late Sunday.

The self-described "lifelong Democrat" said he "will run as a centrist independent outside of the two-party system."

According to Schultz, 65, "We're living at a most fragile time."

Not only is Trump "not qualified to be the president," but Republicans and Democrats "are consistently not doing what's necessary on behalf of the American people and are engaged, every single day, in revenge politics."

Schultz grew up in a working class neighborhood in New York City, but made his fortune when he moved to the northwestern state of Washington in the 1980s and built Starbucks into a global coffee shop behemoth.

Schultz blamed both parties for the country's $21.5 trillion debt, which he portrayed as "a reckless example" of the "failure of their constitutional responsibility."

Schultz dismissed fears that his bid could split the opposition vote and result in a second term for Trump.

"I want to see the American people win. I want to see America win," Schultz told CBS.

At least one Democratic presidential hopeful, Texan Julian Castro, told CNN that if Schultz runs "it would provide Donald Trump with his best hope of getting reelected."

According to Castro, "I don't think that would be in the best interest of our country."

While third-party candidates in U.S. politics often face insurmountable odds, they have played the role of spoilers.

In 1992 conservative billionaire Ross Perot siphoned enough votes away from George H.W. Bush to hand the presidency to Democrat Bill Clinton.

And Democrats blame consumer advocate Ralph Nader for taking votes away from Democrat Al Gore in the 2000 election, allowing Republican George W. Bush to become president. Nader rejects the accusation.