Kamala Harris announced a plan Thursday to end the nationwide backlog of untested rape kits during her first term as president, part of a campaign that has focused on the California senator’s background as a former prosecutor.

Harris said she would spend $1 billion to encourage states to clear rape kit backlogs and invest in reforms, including requiring rape kits to be tested within narrow time frames, counting and reporting untested rape kits, and giving victims information about the status of their rape kits.

Advocates say there are hundreds of thousands of untested rape kits in the country, largely because of a lack of funding and sparse resources in rural and isolated areas — a backlog that results in sexual assault crimes going unpunished. A 3-year-old program by the Manhattan District Attorney’s Office that provides funding to other jurisdictions to test backlogged rape kits has tested more than 55,000 kits, leading to nearly 200 arrests and 65 convictions, at a cost of $38 million.

As a young prosecutor, Harris focused on child sex abuse and trafficking, and as San Francisco’s district attorney, she created a unit centered around child sex crimes. But she has also been criticized in recent weeks for her record with victims of sexual abuse by clergy members.

Despite speculation that Harris’s law enforcement background might hurt her standing with progressives and black voters, her campaign has focused increasingly on her prosecutorial background as she tries to make an argument for taking on President Donald Trump.

After a breakout performance in the first Democratic debate earlier this month, Harris told a crowd in Iowa that she had spent her career prosecuting criminals. “I know predators, and we have a predator living in the White House,” she said.