MANCHESTER, N.H. -- Whether the Senate ever reconsiders gun-control legislation could be decided this week as groups pushing for stricter gun laws plan to mobilize supporters here and in other states with senators who recently voted against a bipartisan plan to expand the national gun background check program.

Sen. Kelly Ayotte (R-N.H.). (AP)

New Hampshire, with its deep-rooted tradition of activism and interaction with its political leaders, is a key test case. Several gun control groups, including Mayors Against Illegal Guns, the group founded by New York City Mayor Michael Bloomberg (I), hope to spend the week pressing Sen. Kelly Ayotte (R-N.H.) to explain why she was the only Northeastern senator to vote against the background check plan, which was the cornerstone of the gun legislation recently defeated in the Senate.

Ayotte plans to host at least three town hall meetings during the week-long congressional recess and is expected to be greeted by angry demonstrators and voters at each stop. Even if the groups can't compel her to change her vote, they vow to drive up voter awareness and anger and sustain the push until Ayotte faces reelection in three years.

"I have worked on a lot of issue campaigns in this state and I've never seen this level of natural momentum on any issue," said Judy Stadtman, a founder of Project for Safer Communities N.H., which is one of several liberal groups working together across the state to track the senator this week.

As she travels across New Hampshire, Ayotte need only turn on the radio to hear some encouragement, as the National Rifle Association and National Shooting Sports Foundation, a firearms industry trade association, began airing radio ads here Monday to thank the senator for her vote.

In the NRA ad, which is airing on several popular talk and music stations, a female announcer bemoans politicians who "care about their power" instead of the safety of children.

"Kelly Ayotte is not just a senator, she's also a mom, who cares about protecting our kids," the announcer says. "She knows the only way to prevent tragedies like Sandy Hook is to fix our broken mental health system. That's why Kelly Ayotte brought Republicans and Democrats together on a bipartisan solution. And it's why Kelly had the courage to oppose misguided gun-control laws that would not have prevented Sandy Hook."

Listen to the NRA ad here:

The NSSF ad, also airing on talk and music stations, not only thanks Ayotte, but also calls out gun-control groups, including Bloomberg's.

"Thank you for standing up to political pressure from a big city mayor who thinks he knows what's best for the rest of us," the NSSF ad says. "Thank you for protecting the rights of gun owners, hunters and all who cherish the freedoms of our Second Amendment."

Listen to the NSSF ad here:

NRA spokesman Andrew Arulanandam said the group is running a similar ad in Kentucky to support of Senate Minority Leader Mitch McConnell (R-Ky.). Larry Keane, the senior vice president and general counsel for NSSF, said his group is airing similar ads in Alaska, Arizona, Arkansas, Kentucky and North Dakota, where senators of both parties also voted against the background check proposal and on other amendments to ban military-style assault weapons and to limit the size of ammunition magazines.

So which will prove more effective -- a radio ad war or angry constituents at town hall meetings? Stay tuned -- we'll have more later today.

Follow Ed O'Keefe on Twitter: @edatpost