BETTENDORF, Ia. — U.S. Sen. Kamala Harris said she envisions a "Medicare for All" health care system that does not include private insurance.

"There will eventually not be a need for private insurance because there will be full coverage, in terms of most of the services that folks need, in terms of access to health care," Harris said at a forum in Bettendorf on Tuesday sponsored by AARP and the Des Moines Register.

The forum, aimed at highlighting the issues facing aging Americans, included appearances by New York Sen. Kirsten Gillibrand and former Housing and Urban Development Secretary Julián Castro.

Gillibrand laid out a Medicare for All program that includes a transition away from private insurance, but allows private insurance to compete with the federal government. She believes the public option will eventually out-compete private companies.

Castro said he believed in a Medicare for All system involves the option of private insurance. "If somebody wants to have a private health insurance plan that they're happy with, that is a solid, strong plan, I believe they should be able to hold on to it," he said.

In a crowded 2020 field, the topic of Medicare for All appears to offer the clearest distinction between the candidates. One day and a few hundred miles apart in the first-in-the-nation caucus state, other candidates offered vastly different approaches to the future of America's health care system.

At the first AARP and Register forum in Des Moines on Monday, Biden highlighted a newly released plan that would introduce a public option within the Affordable Care Act. Biden said he did not anticipate a phase-out of private insurance, as many other candidates have proposed.

Harris, a California senator, said she supports supplemental private insurance that exists under the current Medicare program for seniors, but would phase it out along with other forms of private insurance.

Harris said it is not her intention to create job loss in Iowa, which is home to several insurance companies. She said she's committed to a transition period that ensures everyone has work.

On Tuesday, before the forum, Harris released a plan that she said would target pharmaceutical companies' "gouging." At the forum, she said her administration would punish "patent-parking," a system by which drug companies keep generic drugs from coming to market.

"For those that are exceeding the rules, we could actually take their patent," Harris said, to gasps, and then applause, from the audience.

All three Democratic presidential candidates at Tuesday's forum discussed similar policy ideas on how to tackle high prescription drug prices and keep Social Security sustainable. They supported ideas that included importing cheaper drugs from countries like Canada and addressing loopholes on patents that allow pharmaceutical companies to charge more money for drugs. They also agreed that it’s important to address age discrimination in hiring practices.

Gillibrand said she was open to a universal basic income for people who take care of family members full-time, though she’s still fleshing out the details. She appeared on stage on the same day she released her “Aging With Dignity” plan, which proposes increasing Social Security benefits, among other provisions.

“Unfortunately, we just haven’t dreamed big enough for the last 30, 40 years,” Gillibrand said.

Castro, who's come to Iowa following a strong performance in the first Democratic primary debate, highlighted his contention that improving the country's immigration system could bring employment opportunities that strengthen American’s health care system. He said the immigration system can involve strengthening the border while offering compassion to immigrants.

"If I'm elected president, I want you to know that I'm going to keep my eye on the ball," he said.

Shelley Klaas, a 63-year-old retiree from Davenport, said while the range of issues discussed Tuesday are important to her, she's most concerned with who can beat President Donald Trump in 2020.

"I want to be a person who's all about the issues," she said. "But honestly, when it comes down to it, it is critical to me that we don't have another four years of this."

Outside the event, McDonald's workers with the Fight for Fifteen movement rallied for a higher minimum wage and a union. Both Castro and Gillibrand spoke at the rally and offered their support.

Echoing themes from inside the venue, the rally focused specifically on older workers who were unable to retire comfortably.

Sonya Sayers, 56, worked at McDonald’s for 21 years before retiring. She said she struggles to pay for essentials like medicine, rent and food. “I hate for someone that’s worked as long as I have to have no retirement, no savings," she said.

The event was originally supposed to include Eric Swalwell, but the California congressman dropped out of the Democratic primary race earlier this month.

Three more such forums, featuring a total of 11 more Democratic presidential candidates, will be held this week. They will be in Cedar Rapids, Sioux City and Council Bluffs.

Barbara Rodriguez covers the Iowa Statehouse and politics for the Register. She can be reached by email at bcrodriguez@registermedia.com or by phone at 515-284-8011.