Sen. Bob Casey Jr. (D-Pa.) has won reelection over businessman Tom Smith (R).

Casey leads Smith by 51 to 46 percent with 3 percent of precincts reporting. Multiple networks have called the race.

The centrist senator had been favored for months, but Smith spent millions of his own money and some Democrats complained that Casey had been slow out of the gate to campaign. Polls had shown a tightening race in recent weeks, though Casey still held a comfortable lead in most reputable polling.

The race is one in a number of long shots Senate Republicans had been holding out hope for in recent weeks that have already been called for Democrats. They've also held onto seats in Florida and Connecticut and picked up a seat in Maine.