WASHINGTON (AP) -- The Republican chairman of a House investigative panel says he's concerned about allegations that Secret Service agents cavorted with prostitutes in Colombia, saying such activities would severely compromise presidential security.

California' Darrell Issa (EYE'-suh) tells "CBS This Morning" that lawmakers will "look over the shoulder" of the agency as it investigates the recall of 11 agents from Colombia. The Summit of the Americas, which President Barack Obama attended in Colombia, went on over the weekend without incident.

Issa says the incident is "part of a pattern of misbehavior" involving agents.

He calls it the flip side of the so-called "wheels-up-party", in which agents celebrate once a president's visit is complete and the chief executive has headed home. The congressman says that in the current incident, "you had a pre-wheels-down party."