Robin Kelly celebrates her special primary election win for Illinois' 2nd Congressional District. (AP Photo/Charles Rex Arbogast)

Robin Kelly, who as a young state representative sponsored gun-safety legislation with state Senator Barack Obama, swept to victory Tuesday night in an Illinois US House primary that sent a powerful signal about the National Rifle Association’s dwindling influence within the Democratic Party.

Kelly won 58 percent of the vote in a crowded field, easily defeating former Congresswoman Debbie Halvorson and other Democrats to win the nomination to replace former Congressman Jesse Jackson, Jr., as the representative from Illinois’s 2nd district.

In a multiracial district that includes parts of Chicago, as well as suburbs and rural regions of a district that stretches across northeastern Illinois, Halvorson began the race as the front runner. In addition to her status as a former House member, she was the only white candidate in a field where the African-American vote was divided among more than a dozen contenders.

After the Newtown, Connecticut, shootings focused the attention of the country—and Illinois—on the gun debate, however, Kelly made support for gun-safety legislation central to her campaign.

Kelly’s “Help Me Fight Gun Violence” message united African-American and progressive white voters against Halvorson, who had accepted NRA support in previous races and who continued to support NRA positions on many issues.

Though President Obama, who has made te fight for gun-safety legislation a priority of his second term, stayed out of the race, Kelly promised to champion legislation backed by the president—who her ads noted she had worked with a decade ago, when they both served in the Illinois legislature.

As she claimed victory Tuesday night, Kelly told her backers, “Today you did more than cast a vote. You did more than choose a Democratic candidate for Congress…You sent a message that was heard around our state and across the nation; a message that tells the NRA that their days of holding our country hostage are coming to an end.”

New York Mayor Michael Bloomberg, who has pledged to fight the NRA’s political influence nationwide, used his Independence USA political action committee to air more than $2 million to oppose Halvorson and back Kelly.

The Illinois Rifle Association, an NRA affiliate, backed Halvorson with late-stage mailings.

But it was Kelly’s steady focus on the gun debate that gained her the upper hand in the race.

The NRA and its apologists will, of course, claim that the Illinois district was a bad battleground for the group and its message. Illinois is not West Virginia or North Dakota, after all. And the Chicago area has bitter experience with gun violence, as Kelly noted in a campaign that focused on the anger and pain felt in neighborhoods where too many young lives have been lost to shootings.

But advocates for tougher gun laws recognized the significance of the Illinois result.

“Robin Kelly’s victory tonight is a withering blow to the NRA and others who think we shouldn’t do anything to prevent the gun violence that took the lives of 20 children in Connecticut in December and ravages the streets of cities like Chicago every single day,” announced Arshad Hasan, the executive director of Democracy for America, which backed Kelly. “This was the first time since the tragedy of Newtown that advocates for gun violence prevention have taken on the NRA and their allies—and we won. We’re incredibly proud of the over $15,000 and hundreds of volunteer hours Democracy for America members contributed to Kelly’s win tonight, because we know she’ll fight in Congress for the stronger, common sense gun laws that most Americans support.”

Whatever the dynamic of the district and the state, there is no question that Halvorson had initial advantages that were undone by her association with the NRA and by Kelly’s decision to run on a five-point pledge that declared she would work to:

1. Pass a comprehensive ban on assault weapons.

2. Eliminate the gun show loophole.

3. Pledge never to receive support from groups that oppose reasonable gun safety legislation.

4. Ban high capacity ammunition magazines.

5. Support laws that prohibit conceal-and-carry permits.

“While we don’t know who will represent Illinois’ second district in Congress, we do know that addressing the issue of gun violence will be among the very first issues they face,” Kelly declared early in the campaign. “I believe we need more leaders in Congress addressing the issue of gun violence in our cities and our communities. For this reason, I believe we must all speak with one voice on this urgent matter.”

Primary voters in the 2nd district of Illinois spoke with that united voice Tuesday. And they said “no” to the NRA. Loudly. Perhaps so loudly that Democrats in Congress, many of whom have been cautious gun-safety advocates, will help Robin Kelly fight gun violence.

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