Sen. Mark Pryor's new advertisement defends his vote on background check legislation.

By Michael A. Memoli

May 31, 2013, 8:18 a.m.

WASHINGTON -- As some Democrats argue that the politics of the gun issue have changed, the first ad run by one of the party's senators highlights his vote against expanded background checks for gun purchases.

The message from Arkansas Sen. Mark Pryor reflects the challenge to both gun-safety advocates and conservative Democrats in the next election. Pryor, who faced no Republican challenger in his last campaign, is now stressing his independence as he girds for a difficult race for a third term.

In the ad, Pryor notes that a group founded by New York Mayor Michael Bloomberg is running ads against him for his vote against what he called "President Obama's gun control legislation."

"No one from New York or Washington tells me what to do. I listen to Arkansas," Pryor says.

All 23 of President Obama’s gun policy proposals

Bloomberg's group, Mayors Against Illegal Guns, launched an ad against Pryor last week. Pryor is one of two Senate Democrats running for reelection next year, and four Democrats overall in the chamber, who did not support the proposal by Joe Manchin III (D-W.Va.) and Patrick J. Toomey (R-Pa.) to require background checks for all commercial gun sales. Alaska Sen. Mark Begich (D-Alaska) is the other.

Mayors Against Illegal Guns has also run ads against two Republicans, Kelly Ayotte of New Hampshire and Jeff Flake of Arizona, but neither is up for reelection next year. Supporters of stricter gun laws have no obvious Republican targets for the current election cycle, leaving them only able to target Democrats.

Pryor says in his ad that he does support "real solutions to gun violence" that would protect 2nd Amendment rights, but that the measure by Manchin and Toomey wouldn't have prevented tragedies such as the one in Newtown, Conn., or in his state in 1998 that left five dead at a middle school.

PHOTOS: The debate over gun control

Likewise, Republicans such as Ayotte and Flake who have been criticized for their votes on the issue have said they support steps to reform the background check system, citing their support for an alternative Republican proposal that was also defeated in the Senate last month. Pryor voted for that measure.

Pryor is the only Democrat remaining in the congressional delegation from Arkansas, a state that has trended sharply in favor of Republicans in state and federal elections over the last decade.

Follow Politics Now on Twitter and Facebook

michael.memoli@latimes.com

Twitter/@mikememoli