This is story related so cannot be missed.
After collecting the GPS from the stage, follow the marker to the North to where the President is. As you will be fighting soldiers I suggest you stack up on ranged weapons, such as assault rifle/ZAR. Head up to the front of the house (watch out for the laser trip wires), then you are instructed to find another entrance. Go left round the back, taking out the army/special forces guys. You need to kill them all before a guy will burst out of the back, allowing you access into the house.
The President is upstairs on the left - it only highlighted where she was when I had killed all enemies in the house. Pick up the key dropped by the agent nearby to unlock the door, and watch the cutscene. Good luck!!