Speaking late Tuesday on the CBS 'Late Show,' host Stephen Colbert asked Clinton to explain why he thought that Trump - currently leading a pack of 15 Republican presidential hopefuls - was doing so well.
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"He's a master brander, and he's the most interesting character out there ... and because he says some things that overrides the ideological differences," Clinton said.
"There is a macho appeal of saying I'm just sick of nothing happening. I make things happen. Vote for me."
Clinton however said that Trump's success "may have a short shelf life."
The former president (1993-2001) denied a rumor that he urged Trump to run for president.
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"His daughter told my daughter that he had tried to call me and I didn't get the message. So I simply called him back," said Clinton. "I had a very pleasant conversation with him and it wasn't about running for office."
Clinton's daughter Chelsea is a close friend with Trump's daughter Ivanka, according to US news media reports.
And who does he think is the most qualified to be elected president next year? "The lady I saw singing on 'Saturday Night Live,'" he answered.
That would be his wife, former secretary of state Hillary Clinton, who appeared on the comedy TV show on Saturday.
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