Washington (CNN) A former spokesman for Hillary Clinton is sounding off on Donald Trump -- and warning Democrats not to underestimate him.

Jay Carson was Clinton's 2008 press secretary and worked for her family's foundation, and he recently took to Instagram to sound the alarm on the GOP presumptive nominee.

"Here's the bad news -- this guy can win the general election pretty damn easily," Carson, who is now a producer on the Netflix series "House of Cards" and a Principal at Bloomberg Associates, wrote on his private account. "I hear far too many of my liberal friends calling him a 'joke' and acting like the general (election) is in the bag which is nuts because he's dangerous and he has a path to victory."

Carson told Democrats that underestimating Trump would be perilous.

"Being profane and not reading the New Yorker are not disqualifying characteristics to many Americans," Carson wrote. "Remember, the NPR crowd thought George W. Bush was a 'joke' too and GWB looks like Thomas Jefferson compared to Trump in terms of danger for our country. We underestimate this guy at our peril."

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