Generation Forward, the Super PAC supporting Democrat Martin O’Malley, is up with a video advertisement hitting Bernie Sanders on the issue of guns.

“Bernie Sanders voted against the Brady Bill," a narrator says in the new 15-second ad. "Bernie Sanders is no progressive when it comes to guns.”

In an interview on NPR, Sanders argued that – because he represents Vermont – he has different views on guns that some other Democrats. "I can understand that if some Democrats or Republicans represent an urban area where people don't hunt, don't do target practice; they're not into guns. But, in my state, people go hunting and people do target practice. Talking about cultural divides in this country, you know, it is important for people in urban America to understand that families go out together and kids go out with their parents and they hunt and they enjoy the outdoors and that is a lifestyle that should not be condemned."

Recent polls have shown Sanders’ support growing – though maybe more at the expense of challengers like O’Malley than at Hillary Clinton’s expense.