(1) Does the "term" mean "a period of time that is assigned to a person to serve" in the pic?
(2) What does "the little engine that could" mean? "Little engine"= "little locomotive"?
Context:
"We have been the little engine that could, and I am proud of what we have done together," the smiling Mr. Edwards told a throng of cheering supporters in Atlanta. He said he had called to congratulate Mr. Kerry for a "strong, powerful campaign," and that the two shared a deep commitment to social justice.