Clinton campaign manager: We haven't found our 'Donald Trump' yet for debate prep

The Clinton campaign is still looking for someone to play Donald Trump in preparation for the presidential debates in September and October.

In a Sunday interview on CNN's "State of the Union," Clinton campaign manager Robby Mook said they haven't settled on an opponent to play the outspoken Republican presidential nominee because he's difficult to mimic.

"It's very hard to find someone to mimic the reckless temperament and the hateful instincts and divisive instincts of Donald Trump. Preparing for a debate with him is a challenging task," Mook said.

Mook denied that the campaign was having difficulty finding someone willing to criticize the Democratic presidential nominee and raise sensitive potential lines of attack.

"She has been in this game a long time. She has had a lot of tough things said to her. That's not the challenge here," Mook said.

The Clinton campaign is keeping its debate prep under wraps. But Politico recently reported that the campaign is readying the former secretary of state to face questions with a personal and conspiratorial bent. Some observers have speculated that potential picks to play Trump include Sen. Al Franken, a former "Saturday Night Live" cast member and comedian, and former Pennsylvania Gov. Ed Rendell, who joked recently that his proclivity for Trump-like outspokenness could make him a good debate sparring partner.

For its part, the Trump campaign appears to be preparing for the debate already. The real-estate magnate reportedly sought advice from former Fox News CEO Roger Ailes in his debate-prep sessions, though the campaign has denied Ailes' involvement.