Bernie Sanders spoke in Des Moines, Iowa on Saturday where he issued a rallying cry for "a vibrant American democracy," and took aim at the Republicans' healthcare bill, which he called "the most anti-working class legislation" in modern history.

The Vermont senator made the remarks at the Iowa Citizens for Community Improvement (CCI) Action Fund's annual convention called "Revolution Iowa: From Protest to Power," where he delivered the keynote address.

Sanders said that "we're in a pivotal moment of American history."

he trend toward having a handful of billionaire families with unlimited resources controlling our political process will only get worse. The trend toward a handful of conglomerates owning and controlling our economy will only get worse."

"And what our job is," he continued, "is to create a vibrant democracy where one person, one vote is what dominates the political system, not billionaires buying the election."

"Democracy is facing an enormous challenge," Sanders said.

Threats to a "vibrant democracy," he said, come not only from the "disastrous" Citizens United Supreme Court ruling, but also "Republican governors, cowardly governors, who don't have the guts to run for office based on their ideas but who are attempting to suppress the vote to keep low-income people or people of color or working people or older people from participating in the political process."

"If some Republican wants to run for office talking about giving tax breaks to billionaires and cutting Social Security and Medicare and Medicaid and education, that is his or her prerogative. Run for office on those ideas. See how many votes you get."

His advice for politicians espousing those ideas but not willing to run for office on them? "Get out of office or get another job."

Among the steps to ensure that everyday Americans—"not the Koch brothers"—dominate the political process, Sanders said, are establishing automatic voter registration, restoring the voting rights for convicted felons who've served their sentence, ending superPACs, and enacting public funding of elections.

Sanders also took direct aim at Donald Trump, saying the president's claim that three to five million people voted illegally in the 2016 presidential election "is an absolute lie" whose goal is "to encourage state officials all across the country to suppress the vote. We will not accept that."

Trump, he added, "is supporting the most anti-working class legislation ever presented in the modern history of this country—a disastrous healthcare bill."

"President Trump, don't tell the people of this country that you support the working class when you are defending legislation which will throw 22 million Americans off of the healthcare they currently have," Sanders said. "That is not defending the working class. That is a major attack on middle class and working-class families all across this country."

Addressing his Senate colleagues in the Hawkeye State, Republicans Chuck Grassley and Joni Ernst, he said, "please, please take a hard look at what this disastrous legislation will do to the people of Iowa and the people of America."

"I beg of them: please vote 'no' on this legislation," Sanders said.

The former presidential candidate, who last week said a 2020 White House bid wasn't "off the table," told the crowd: "We are going to fight for an American democracy that will make future generations proud."