Hillary Clinton promised to continue to fight for tougher gun control on Tuesday during a campaign event that paid tribute to the victims of gun violence and police brutality.

“The epidemic of gun violence spares no one, but it is concentrated in areas that are short on hope,” Clinton said on Tuesday during a panel discussion on gun violence at Tabernacle Community Baptist church in Milwaukee.

Clinton has made gun control a pillar of her campaign. She has called for strengthening background checks and closing a number of loopholes that enable unmonitored gun sales, while promising to take on the National Rifle Association – a lobby group, she reminds voters, that holds near-supreme power in some parts of Washington.

“This needs to be a voting issue,” Clinton said of the fight to tighten gun laws. “Not number 20 on the list, number one on the list.”

Clinton is on a two-day campaign swing through the state. On Monday, she forcefully derided Republicans for refusing to hold a hearing on Barack Obama’s supreme court nominee and called on Democrats to make the issue a reason to bring voters to the polls. On Tuesday, she will hold rallies in La Crosse and Green Bay.

In 2008, Clinton ran to the right of Obama on guns, criticizing him for being out of touch with the tens of thousands of Americans who own firearms and use them responsibly. But this time, she has seized on the issue as a point of difference between her and Sanders, who represents a pro-gun state with a strong hunting culture and very low crime.

She has hit Sanders for his support of legislation that in effect shields gun manufacturers from legal liability for “criminal misuse” of the weapons. Sanders has since shifted his position and said he supports a reform measure that would repeal this part of the law.

At the church, Clinton sat between Representative Gwen Moore, a Democrat from Wisconsin; Geneva Reed-Veal, whose daughter, Sandra Bland, was found hanged in a jail cell three days after being pulled over for a minor traffic violation in Houston last July; and Annette Nance-Holt, whose 16-year-old son, Blair Holt, was shot dead in 2007 when a man opened fire on a Chicago bus he was riding.

“How could this happen to my child in America?” Nance-Holt asked, as one woman seated in a pew sobbed audibly.

Clinton used the issue to obliquely attack her rival Sanders, who is mounting a strong challenge in Wisconsin after a string of victories last week. Nance-Holt, however, was not so coy.

“If you want my vote, you better work for it,” Nance-Holt said, after noting that Clinton had been the only Democratic candidate to reach out to her. She implored the audience to vote for the candidate who has prioritized gun violence and cautioned them against giving too much weight to the Vermont senator’s proposal to make college free for all students.

“I’m not going to give it to you just because you say you want to give kids free college, because if my child is dead, he can’t go to college,” she said.

The “mothers of the movement”, women who have lost their children to gun violence and police brutality, have served as powerful surrogates for Clinton on the campaign trail. During the event, Reed-Veal reiterated that the mothers are not being “exploited” by Clinton and said they were freely backing her because she cared enough to reach out to them and listen to their stories.

Last Christmas, Clinton sent Reed-Veal a card, she recounted. “I know this is the first holiday without your baby,” she said the card read.

Clinton pledged that as president she would continue to wage the fight for better gun control, while acknowledging that stopping the epidemic of gun violence required fights on multiple fronts. She cited mental illness, the gun lobby and a shortage of opportunities as key obstacles.

“Let’s not grow weary doing good,” Clinton said, paraphrasing Galatians 6:9, “because in due time we will harvest if we stay focused.”