IOWA CITY — Heading into the final month ahead of the 2014 midterm election, Vermont Sen. Bernie Sanders exhorted fellow progressives to plug away at the unglamorous nuts-and-bolts of the campaign against a “billionaire class whose greed knows no bounds.”

“Everyone in this room understands participating in the political process is the most patriotic thing we can do,” Sanders, the U.S. Senate’s longest-serving independent, told about 400 people Sunday at the Johnson County Democratic barbecue.

The polls and prognosticators may paint a bleak picture for the party in the Nov. 4 election, he said, “but if we stand together, there is nothing we cannot accomplish for our great country.”

“While the Koch brothers and the billionaire class have the money, we have the people,” he said.

Sanders, 73, a self-described democratic socialist who is considering a bid for the 2016 Democratic presidential nomination, brought the Johnson County Democrats to their feet several times in his half-hour speech that laid out a progressive agenda for increasing Social Security benefits and the minimum wage, offering a single-payer Medicare-for-all health care plan, creating 13 million jobs by investing $1 billion in a federal jobs program to rebuild transportation infrastructure and overturning the U.S. Supreme Court’s Citizens United decision.

In the face of that struggle, Sanders reminded his audience of the progress that has been made.

“These are tough times,” he said. “Change does not come about overnight. Many have fought and died and gone to jail for change.”

As a result, Sanders said, America has elected and re-elected an African American president, elected 20 women to the Senate — and he predicted that in another decade half of the senators will be women — and states are defending same-sex marriage.

“It means that change comes when people struggle, and we have achieved a whole lot,” Sanders said.

However, he said, on the question of whether the nation is going to have a thriving middle class, full employment, jobs that pay people a decent wage and health care for all, progressives are losing ground.

“That struggle we have not won,” Sanders said. The Koch brothers and their allies “want more and more and more and are prepared to destroy the American middle class to get it.”

Sanders, however, has hope.

“I believe that when we stand together, we are going to beat these guys,” Sanders said. “We are going to ask them to start paying their fair share of taxes. We’re not going to let them buy elections.

“And when we do that, we are going to create a nation our kids and grandchildren will be very proud of,” Sanders concluded