Obama hit up Ted’s Bulletin restaurant in D.C. yesterday where he surprised a group of campaign volunteers who had won an essay contest and left quite the tip for the servers that helped him out.

Marisa Mendez

Sources connected to the restaurant tell TMZ … the President ordered a plain cheeseburger, fries, and side salad … and an ice cold glass of water to wash it down.

We’re told Obama asked for the bill personally — and picked up the tab for the entire group on his credit card. In total, with tip, Obama dropped over $200.

One person who was inside the restaurant tells us, “He couldn’t have been nicer.”

The “surprise” wasn’t as impromptu as it seemed … we’re told secret service swept through the restaurant with a K9 unit earlier that day — and the restaurant was closed to the public.