HARRISBURG, Pa.—The race for U.S. Senate in Pennsylvania cost about $40 million, ending in the re-election of Democratic U.S. Sen. Bob Casey for a second six-year term.

The campaigns released information Thursday in conjunction with a federal reporting deadline. Casey beat his better-financed but lesser-known Republican challenger, Tom Smith, 54 percent to 45 percent.

Almost $30 million of the total amount, including money from outside groups, was spent after July 1. Smith spent almost $21 million, mostly his own money. Casey spent about $12.5 million in the two-year campaign cycle.

Including contributions from outside groups, Smith outspent Casey by nearly 2-to-1. The cost was substantially less than the 2010 election in which Pat Toomey beat Joe Sestak to take Arlen Specter's Senate seat. The cost of that election exceeded $50 million.