here is the recipe -
http://www.senate.gov/reference/refe.../bean_soup.htm
"Senate Bean Soup
Bean soup is on the menu in the Senate's restaurant every day. There are several stories about the origin of that mandate, but none has been corroborated.
According to one story, the Senate?s bean soup tradition began early in the 20th-century at the request of Senator Fred Dubois of Idaho. Another story attributes the request to Senator Knute Nelson of Minnesota, who expressed his fondness for the soup in 1903.
The recipe attributed to Dubois includes mashed potatoes and makes a 5-gallon batch. The recipe served in the Senate today does not include mashed potatoes, but does include a braised onion. Both Senate recipes are below."