Tonight on Hannity, Newt Gingrich went off on President Obama for urging Republican leaders to withdraw support for Donald Trump and calling the GOP nominee "unfit to serve."

Gingrich said that it was "pretty despicable for a President of the United States to be that harsh about his potential successor."

"I mean, talk about undermining the United States of America, President Obama potentially did that today."

Gingrich also went off on Obama for criticizing Trump for not knowing things when the president was wrong on keeping your doctor under Obamacare, red lines in Syria, Russia taking Crimea, Iraq collapsing and Chicago murders.

"You go down the list of things Barack Obama doesn't know and it is astonishing the arrogance and the demagoguery of this man in just sweeping away others. I think that the Obama presidency will be looked back upon as one of the great failures in American history."

Watch more above.