Clinton senior strategist expressed 'worry' over Marco Rubio: He 'could pose a real threat'

A senior strategist to Hillary Clinton's presidential campaign wrote top advisers in early 2015 to express concern over the "threat" Florida Sen. Marco Rubio could pose in a general election, leaked emails revealed Wednesday.

"I'm beginning to worry about Rubio than the others," pollster and Democratic strategist Joel Benenson wrote in an email to senior staff, which included campaign manager Robby Mook and chairman John Podesta.

Benenson, who did work for both of President Barack Obama's campaigns, said Rubio, who unsuccessfully ran for the Republican presidential nomination, was "playing this very smart."

"He has stronger right wing red than Jeb and he's finding a way to the middle enough for now and he will be the most exciting choice to Republicans," he wrote. "Could pose a real threat with Latinos etc."

"Just my anxiety thought of the day," Benenson concluded.

While Benenson was worried, Democratic pollster Mandy Grunwald was not. She wrote back arguing that the Florida senator was "very inspiring at his best."

"Feels kind of like a light weight in a lot of interviews - but I take your point," she wrote.

The leaked Podesta emails do reveal the Clinton campaign was paying attention to Rubio. In one particular case, senior staff emailed back and forth in a lengthy exchange about how to best respond to a tweet he posted.

Rubio is currently running for reelection to the US Senate in Florida after his unsuccessful bid for the presidency.