Omar Samaha, whose sister was killed in the 2007 Virginia Tech massacre, and more than ten survivors and family members of victims of Virginia Tech released a new television advertisement Monday.

The ad, which will run statewide this week, calls for closure of a loophole that allows some sellers at gun shows in Virginia to sell weapons without conducting a background check of the purchaser. The ad, which features Samaha, focuses on the former state Atty. Gen. Bob McDonnell, who is the only Virginia gubernatorial candidate who opposes closing the loophole.

Samaha and the survivors and family members were joined by New York City Mayor Michael R. Bloomberg and Tatyana Timoshenko. Timoshenko is the mother of NYPD officer Russel Timoshenko, who was killed in July 2007 by an illegal gun sold by a Virginia gun dealer who was prosecuted for illegal gun sales.

The ad campaign coincides with the second anniversary of the Virginia Tech massacre, which claimed 32 lives, and the tenth anniversary of the Columbine massacre in Colorado. It is sponsored by Americans United for Safe Streets, a non-partisan advocacy organization working to reduce violent crime.

It will begin airing Tuesday for a four-day cable and broadcast run across Virginia, including these markets: Richmond, Charlottesville, Harrisonburg, Norfolk-Portsmouth, Roanoke-Lynchburg, the Tri-Cities and Washington, D.C., which serves Northern Virginia viewers.

“Leaving the gun show loophole open protects criminals, not Virginians,” says Samaha, a 25-year old VA Tech graduate. “I don’t want to wait around to see whose sister is next. No family should have to go through what we’ve suffered.”

As featured on Friday's 20/20 on ABC, Samaha recently attended a Virginia gun show and easily acquired ten high-powered guns, including a Glock similar to the one that killed his sister, with no background check, all in less than an hour.

Although federal law requires gun dealers to conduct background checks on people purchasing weapons, it exempts so-called “occasional sellers,” who often conduct business at gun shows. The loophole provides criminals with easy access to firearms without having to worry about any background checks.

A study by the federal Bureau of Alcohol, Tobacco, Firearms, and Explosives found that about 30 percent of all the guns detected in gun trafficking investigations were connected to gun shows and flea markets. In a poll earlier last year by Christopher Newport University, Virginians ranked closing the gun show loophole as one of the top two priorities for the state legislature.

A bill to close the gun show loophole failed by only two votes in the Virginia senate earlier this year.