Senator Christopher Dodd, who is steering the financial-overhaul bill through the Senate, said last week’s market plunge illustrates the need for the legislation, which is aimed at detecting and alleviating developments that could disrupt the economy. “We need to get in place our bill, have the president sign it, so we have the tools to protect our economy from these kind of events,” Dodd, a Connecticut Democrat, said in an interview. “Our bill is designed to deal with these early warning systems.”