Massachusetts senator and Democratic presidential candidate Elizabeth Warren is continuing to defend her phased-in Medicare For All plan on the campaign trail. After surging to the front of the crowded presidential field earlier this fall, Warren has been slipping in national and early state polls in recent weeks, as she’s faced increased scrutiny for her healthcare plan and her status as a frontrunner.

Warren continued a two-day campaign swing through the state with a stop in Iowa City Monday afternoon, speaking at the Iowa Memorial Union on the University of Iowa campus.

The debate over the expansive single-payer government insurance program has dominated the primary campaign, drawing strong criticisms from more moderate candidates as an extremely costly and far-reaching approach that would ultimately mean transitioning millions of Americans off their current private insurance.

Before the event in Iowa City, she defended her plan to phase in a staggered Medicare For All program over her first term in an interview with Iowa Public Radio. Warren argues that once Americans have received broader healthcare benefits they won't want to give them up.

“Sure, the next president after me could come in and say, let’s raise the price of epipens and insulin, but I also think that’s going to be like walking into a buzz saw,” Warren said.

"I think when people experience it, they see how it works, they see how medical decisions are just between the patient and the healthcare provider and not an insurance company, I think that’s going to have a lot of folks saying, I want to hang on to this,” she added.

Last month, Warren announced the $20.5 trillion price tag of new federal spending for her Medicare For All program, which she intends to fund through a series of mechanisms, including through higher taxes on wealthy individuals and corporations as well as redirecting funds from cuts to military spending.

In November she also announced her intention to delay rolling out the full implementation of Medicare For All. Instead, she would allow Americans to opt in to the government insurance program or keep their private insurance in the early years of her term, essentially a public option.

Warren has criticized the public option plans of her moderate competitors in the past, arguing the programs would disadvantage Americans with lower incomes.

The Massachusetts senator intends to transition the entire country to Medicare For All by the end of her first term.

In an abbreviated version of her stump speech at the University of Iowa, Warren did not speak about her healthcare plan, instead focusing on her biography of growing up in Oklahoma before becoming a public school teacher and ultimately a lawyer and law professor.

But when the issue came up in a question and answer session with likely caucusgoers, she took the opportunity to speak broadly about her plans to expand social services in general and healthcare in particular.

"How do we make this country work for everyone? Whatever their age and whatever their ZIP code, whatever their race. We just want a country that kind of works for everybody," Warren said. "We can do that by making sure that we just ask those at the top pay. This is not something that we're gonna need to raise taxes on middle class families by one single penny."