Hillary Clinton's Communication Director, Jennifer Palmieri, has told ITV News Donald Trump's performance was a surprise.
She said: "Not the debate we expected as we thought Trump would be more disciplined. Not only did he lose ground on attracting African American voters, he basically said he'd been "smart" not to pay taxes.
"He dug a hole deeper on Iraq and on the Birther lie. The debate was a microcosm for why he's not qualified to be President."
Her views were echoed by Clinton supporter Brigadier General John Douglass, who believes Trump was "erratic" and has "no knowledge".
"I think she demonstrated clearly she has the knowledge, experience and temperament to become commander of the US forces. Trump's erratic, his facial expressions...everything he showed tonight show he has no temperament and no knowledge.
"What I saw tonight made me even more concerned than I was before if Trump were to become President. If you're a volatile character that's a pretty scary prospect with our finger on the nuclear button".