A 30-second ad for incumbent Republican Porter began running Wednesday on network channels in Las Vegas. The first ad for Democrat challenger Titus, a state senator, goes on the air tonight, a spokesman said.

Porter's commercial focuses on energy costs, an issue front and center in a summer of $4-a-gallon gasoline. It was filmed in part at Nevada Solar One in Boulder City, the world's third-largest sun-powered electricity plant.

Appearing beside solar panels and in a plant control room, Porter says that he "helped build" the facility and that solar power is "inexpensive and safe for the environment."

"But it is going to take more than just solar," he says. "We need to act, and that means increased domestic drilling and exploration to give us some relief at the pump today."

The commercial will run for a week on network TV in Las Vegas, Porter spokesman Matthew Leffingwell said. How often it would run was unclear. Production and airtime costs were $104,000, which were split between Porter and the National Republican Congressional Committee.

Besides direct spending by Porter, the committee has set aside $590,000 for Las Vegas airtime during the fall.

Meanwhile, the Democratic Congressional Campaign Committee has allocated $916,000 for local airtime to promote Titus.

The commercial, which does not identify Porter's party affiliation, is the first of what is expected to be a barrage of television spots in the race.

The 3rd Congressional district includes Henderson, Boulder City, Laughlin, parts of Summerlin and parts of unincorporated Clark County east of Las Vegas.

Titus has several commercials ready, and which one would be the first to air was unclear, spokesman Andrew Stoddard said.

As to Porter's ad, Stoddard said any Porter role in what became Nevada Solar One took place years ago when he was mayor in Boulder City.

Democrats contend the Republican has been sympathetic to "Big Oil" during his six years in Congress.

Porter was mayor in 1990 when the Boulder City Council offered to buy 107,000 acres of former federal land in the Eldorado Valley for recreation, a desert tortoise preserve and a "solar power peaking station."

Porter was a state senator, and no longer mayor, when the sale was finalized in 1995.

The 400-acre Solar One facility, which company executives said provides enough electricity to serve 14,000 homes, was opened in June 2007.