Secret Service was aware of the potential threat 10 minutes before Donald Trump took the stage

JUST IN: Secret Service was aware of the potential threat 10 minutes before Donald Trump took the stage in Pennsylvania but let him go out anyway.

The revelation was made during a Senate briefing today.

Sen. Marsha Blackburn says she was "appalled to learn the Secret Service knew about a threat prior to President Trump walking on stage."

"I have no confidence in the leadership of Director Cheatle and believe it is in the best interest of our nation if she steps down from her position."