"Do you understand that size of the organizations you are talking about? I doubt that it can be done in an hour, given the level of security held by secret service agents working in the president's detail."

Umm... it's not that hard. Pick up cell phone. Call supervisor. He calls someone on his contact list, say.. Superintendent of Maryland State Police. At home. In bed. Sup calls Airport and says: "Let him through or you are all working a trash detail for the rest of your lives".

Agent on plane.

Seriously, the Secret Service absolutely has duty officers at communications facilities 24/7 who can reach out to another agency any minute of any day.

The whole :
"This is the White House calling, please stand by" has an AMAZING way of making people pay attention.

Regards,
-Bouncer-