DES MOINES, Iowa (AP) — Republican Sen. Joni Ernst and Democratic challenger Theresa Greenfield differed sharply Thursday about whether systematic racism exists and whether either had benefited from white privilege.

The two candidates joined for their final televised debate as thousands of Iowans were already voting by absentee ballot and the Nov. 3 election was less than three weeks away. The candidates spoke on numerous topics from remote locations, with Greenfield at an apprenticeship training facility in Altoona and Ernst in Washington.

The race is among the most expensive in the nation and could be a key to whether Republicans can retain control of the U.S. Senate.

The issue of systemic racism has come up in earlier debates as Ernst has argued that because Greenfield has professed her belief in systemic racism, the Democrat is saying police are racist. Ernst repeated that claim during Thursday's debate.

Ernst said she doesn't believe there is systematic racism in police departments, though she added that certain people are racist and the country has opportunities to do better.

“I believe that there are many challenges that we have in various systems but I would not say just broadly that we have systemic racism across the board," Ernst said. “Certainly we have good people that are working in all career fields and I think it's important to stress that."

Greenfield rejected Ernst's charge about her believing police are racist, calling it “insulting" and noting her father-in-law was in law enforcement. However, Greenfield said systemic racism has long been a problem in many U.S. institutions, including policing.

“Discussing systemic racism does not mean that any one individual is a racist but rather that we have to take a look at the discrimination across out systems — housing, health care, education, finance and so many other things to ensure we're doing everything we can to end that kind of racism," Greenfield said.

Greenfield said people who can't acknowledge that systemic racism exists can't take the lead in ending such practices.

The candidates were also asked about white privilege and whether as white women they had ever benefited from their race.

Ernst said she didn't know if she had ever benefited from being white and that in Iowa the situation may be more about poverty than race.

“It goes back to maybe not racism but issues of poverty within our communities," Ernst said.

Ernst noted, however, that when she began serving in the National Guard, she was part of a racially diverse system where the key to getting ahead was hard work.

Greenfield said she's sure she has benefited from her race, noting that when her husband died she was a young mother, she survived thanks to Social Security benefits. She also noted the higher infant mortality rates for black women and wondered if the births of her children might have been different if she wasn't white.

“We have to look at why that's happening, what that discrimination is, where is the racial bias, be able to look ourselves and then make sure we're investing in training to address that kind of racial bias in health care, in policing, in education, in the Social Security system, in lending and so many other things," she said.

In response to questions about health care, Greenfield said she was committed to expanding the Affordable Care Act and adding a public options to increase competition and potentially reduce prices. She criticized Ernst for voting to end the ACA even as Republicans haven't offered proposals to ensure millions of Americans won't lose their health care.

Ernst said she was committed to ensuring health care isn't denied to people because of pre-existing conditions, but she supports the repeal of the ACA because it expanded access without reducing costs.

Asked about whether the minimum wage should be raised, both candidates agreed that people couldn't meet all family expenses if paid Iowa's minimum wage of $7.25.

Greenfield said the minimum wage should be increased but even more important would be to invest in community colleges and other programs to ensure people can get jobs that pay far more.

“I support raising the minimum wage but I'll tell you what I'm really focused on and that is making sure everyone has an opportunity to earn a living wage," Greenfield said.

Ernst said the minimum wage is primarily for people just entering the job market and that the issue should be left to state and local governments.

“Economies are so very different across the United States and what might be right for California or New York simply may not be right for our rural communities in Iowa," she said. “A living wage in San Francisco would be very different than a living wage in Red Oak, Iowa, or Waterloo, Iowa."