On the crowded campaign trail, Sen. Bernie Sanders returned to where he got a particularly warm reception during his last presidential run: The University of Iowa campus.

More than a thousand people packed the main ballroom of the Iowa Memorial Union Friday to hear Sanders speak. A few hundred more gathered in an overflow room.

“My only regret is we didn’t get a larger room," Sanders quipped as he introduced himself.

The senator from Vermont stressed income inequality issues, promising to fight for a $15 federal wage, tuition-free higher education, free healthcare and tax reform.

“Downward mobility is not acceptable to me," Sanders said. "It is not acceptable to the American people… This campaign is about moving the American people up, not down.”

He called for rebuilding infrastructure across the U.S., legalizing marijuana, reforming the criminal justice system, reviving rural areas and reducing gun violence.

These pitches, Sanders said, were considered radical the last time he ran, but are now the cornerstone of Democratic campaigns everywhere. He said his last presidential campaign — and the Iowans who gave that campaign an early boost — are why these ideas are more mainstream.

“I began the political revolution in 2016," Sanders said. "And with your help in the campaign, we are going to complete what we started right here.”

In 2016, Hillary Clinton edged out Sanders in the Iowa Democratic caucus by less than one percentage point. But in Johnson County, Sanders dominated, earning 60 percent of the vote.

The University of Iowa was a supportive location for Sanders. Ahead of the 2016 caucus, his largest crowd — around 3,900 — gathered at the UI Iowa Field House.

There are several reasons for his Johnson County support, says Tim Hagle, an expert on U.S. politics at the University of Iowa.

Most obviously, Johnson County is generally regarded as the most liberal county in the state, Hagle says. Most critically, Sanders seemed to appeal to younger voters, similar to the way Ron Paul captivated young voters four years earlier.

Sanders raised issues in 2016 that popular Democratic-socialist politicians like Alexandria Ocasio-Cortez picked up on and used to win elections in 2018.

“There was also kind of a phenom where Bernie Sanders was bucking the system,” Hagle said, noting that there is some irony to this given Sanders' long political career.

Hagle says this time around, Sanders has more name recognition and experience than his current opponents.

Still, Sanders cannot run the same campaign he ran against Hillary Clinton, Hagle said. Four years after his last run, Sanders greeted an almost entirely different voting block on campus Friday.

“We’ve got mostly new students,” Hagle said. “Do they see Sanders as that insurgent candidate?”

University of Iowa sophomore Molly Gunter is still making up her mind on the candidate. Sander's rally is just one of several political events the Democrat will check out before she votes in a presidential election for the first time.

"I'm just kind of looking around," Gunter said. "I mean, there's a lot of people who've said they are coming out."

Other attendees like Cate and Geraldo Garza, of Iowa City, are done deliberating.The two donned handmade jerseys that spelled out "Bernie Sanders 2020" when they stood side-by-side.

"I like that he's not backed by big corporations," said Cate Garza, who says she caucused for Sanders last run. "He's just himself."

One of Sander's younger fans was Ikabod, age 11.

"I wanted to [attend]," said Ikabod, who came to the rally from Muscatine with her parents and two toddler twin siblings. "My mom's been talking about it."

Ikabod's mom, Sharee Byrne, said Sanders addresses the issues she values: access to affordable healthcare, education and the wealth disparity.

"We felt like we should bring our kids, even though it's a pain in the butt," she said. "We want them to see why we are so passionate."