Moderate Republican Sen. Lincoln Chafee of Rhode Island, his political career at risk from a more conservative challenger, led in early returns Tuesday in a contest that could be crucial in the larger fight for control of Congress. With 3 percent of precincts reporting, Chafee had 2,735 votes, or 55 percent, to Cranston Mayor Steve Laffey's 2,241 votes, or 45 percent. The last big day of primaries before the November elections also brought intriguing Democratic contests for Senate in Maryland and a House seat in Minnesota. In all, nine states and the District of Columbia voted, with the other states...