STAMFORD -- U.S. Sen. Joseph Lieberman, D-Conn., is expected to return Monday to Stamford High School, where he campaigned for class president more than 40 years ago, to announce he is running for president in 2004. While supporters expect the Stamford native and the 2000 Democratic vice presidential candidate to announce his presidential bid Monday, a source even closer to the senator -- his mother, Stamford resident Marcia Lieberman -- hinted yesterday that he is already in the race. "He's going to make a great president," she said. ... Marcia Lieberman said she has expected her son to run for...