Harkin, 68, said in prepared remarks it's time to "find ways to work together, not tear each other apart."
The Des Moines Register reported Reed's campaign never gained traction, resulting in what was expected to be Harkin's largest margin of victory of his Senate career.
With 99 percent of precincts reporting, Harkin led Reed 930,426 to 556,205 -- 63 percent to 37 percent.
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