Sen. Bernie Sanders brought his insurgent presidential campaign to Minnesota Sunday, charging up more than 3,000 supporters with his fiery, left-leaning rhetoric about income inequality and money in politics.

Speaking for about 45 minutes at the American Indian Center in Minneapolis, Sanders insisted that the American economy and now its democracy have been broken because too much power has accrued to the wealthy.

“You guys already own much of the economy. Now we’re going to give you the United States government and state governments all over this country. Brothers and sisters, that is not democracy. That is a movement toward oligarchy,” he said in his Brooklyn accent, to shouts and cheers.

The crowd, with some people standing outside because the hall was full, seemed unconcerned with the conventional wisdom that there is no race on the Democratic side as Hillary Clinton marches toward the nomination with a pile of money, endorsements and party faithful’s love of the Clinton name.

The Democratic nominee will face a large and growing field of announced and potential Republican candidates, including former Fla. Gov. Jeb Bush, senators Marco Rubio, Rand Paul and Ted Cruz, Wisconsin Gov. Scott Walker, Dr. Ben Carson and former Arkansas Gov. Mike Huckabee, among others.

Sanders’ straightforward leftism hearkens to the 1960s, and many in the crowd appeared to be veterans of battles over the Vietnam War and civil and women’s rights.

Sen. Bernie Sanders spoke during a rally at the American Indian Center Sunday May 31, 2015 in Minneapolis, MN.

Dr. Bill Wallin, 69 and medical director of a clinic in California that serves undocumented immigrants, said aside from some phone banking for Barack Obama in 2008, he had not been to a political event since the 1968 campaign of Sen. Eugene McCarthy, the Democrats’ antiwar candidate who helped upend the presidency of Lyndon Johnson.

Wallin said Sanders, an independent from Vermont who caucuses with Democrats, is the candidate who will fight what the Oakland physician called “corporate hegemony.”

Sanders, 73 and the one-time Socialist mayor of Burlington, Vt., is filling a hole in the Democratic race left by the absence of Sen. Elizabeth Warren, D-Mass., the star of the party’s liberal wing.

Democratic primary campaigns in recent decades often have featured upstarts who challenged established favorites. Howard Dean was the little-known former governor of Vermont who ran on an antiwar campaign all the way to front-runner status in 2003 before fading. Although he had developed a considerable national following, Obama was a first-term senator against Clinton, who was the heavy favorite until November 2007.

On Sunday, Sanders laid out an agenda in line with the Democratic base, including a major federal infrastructure program to create jobs; a harder line on trade agreements; an increase in the minimum wage; paid sick leave; a tax code with steeper levies on the rich; campaign finance reform; subsidized college for all; and a move toward a socialized health insurance system that would guarantee health care.

Mostly, however, Sanders stuck to the theme of income inequality, an issue gaining so much traction that even some Republican candidates are taking it up, albeit with a different view. Rather than blame the wealthy and their political patrons, Republicans point to sclerotic government and high taxes for the misfortunes of the middle and working classes.

Clinton also has taken up the issue of inequality, perhaps a sign that Sanders is having an impact on the campaign.

Although the enthusiastic crowds may indicate a Sanders boomlet, the reality of a tough slog ahead was already apparent Sunday. During an appearance on “Meet the Press,” he was confronted with a report from Mother Jones magazine about an essay he wrote in 1972 that discusses women’s rape fantasies.

Sanders compared the 1972 essay to “Fifty Shades of Grey” and called it poorly written “fiction” that was an attempt to deal with gender stereotypes.