The President of the United States is the head of state of the United States of America.
The President was relaxing on Air Force One when a Secret Service dude passed on a message from the First Gentleman, Jerry, asking if she wanted meatloaf or roast chicken for dinner. She was just opting for pizza when the plane was suddenly attacked and everyone on it gassed into unconsciousness. The Decepticon Starscream took the plane to the Grand Canyon, where he intended to ransom it for Optimus Prime. When the Autobots turned up, Starscream attempted to use the President's unconscious body as a human shield, waving her around in his hand. Optimus quickly severed his arm, catching the President. She later woke up with a headache and joined the rest of the Air Force One crew in wondering how they'd gotten to the Grand Canyon.