Democrat Matt Heinz is the only congressional candidate in southern Arizona airing television ads as part of his campaign for office.

In his second TV ad, Heinz goes after his Democratic primary opponent, U.S. Rep. Ron Barber. Heinz' first ad focused on his own legislative efforts as a state representative.

The ad criticizes Barber for voting for a bill that "exempted the border patrol from over a century of environmental laws," the narrator says in the ad.

Barber expressed concerns with the bill at the time of the vote, his first day after winning the special election in Congressional District 8 in June.

“He put into the record the ways in which he would have wanted to change that bill, [but] he still feels that you can’t vote maybe and he voted for border security," said Barber's campaign manager, Jessica Schultz.

Heinz is airing the ad, he says, because voters tell him they’re concerned about Barber’s vote.

“This ad is really reflective of something that I think voters need to know about my opponent’s record," he says.

The other candidates in the race, Barber and Republicans Martha McSally and Mark Koskienimi, have not aired TV ads this election cycle.

Watch Heinz' ad: