CEDAR RAPIDS, Iowa, Sept. 10 — After 26 years in Congress, happily cultivating his image as the quintessential Republican moderate, somehow above the partisan fray, Representative Jim Leach suddenly finds himself smack in the middle of the battle for the House. "It's a hard time," he says, sighing, his voice trailing off as he ponders the weeks ahead. Redistricting has forced him into a new Congressional district that is decidedly Democratic. His opponent, Dr. Julie Thomas, is well financed, has strong roots in the community, and makes the case — in the calm, just-trust-me style of a longtime pediatrician —...