Thousands of Bernie Sanders supporters lined up in Minneapolis Sunday morning to see the Vermont senator who's running for president.

Sanders is seeking the Democratic nomination and drew standing ovations as he called for higher taxes on the wealthy, universal pre-kindergarten and solutions to climate change.

In a 40-minute off-the-cuff speech, the Vermont senator — who's running as a Democrat — focused on income and wealth inequality, which he called the great moral issue of our time.

Sen. Bernie Sanders, I-Vt., answered questions during a press conference at the U.S. Capitol Jan. 16, 2014, in Washington, D.C. Win McNamee | Getty Images 2014

One of the supporters at the event, Max Wallin, 30, is an Iraq War veteran from South St. Paul. He said he supports Sanders' campaign because of his early opposition to the war.

"I think the biggest thing for me was that he was one of the very few people who actually voted against authorization of force for going into Iraq."

Prior to the event, Sanders appeared on NBC's "Meet The Press" and called for presidential debates to begin as soon as July. He said the debates should include both Republicans and Democrats.

A Quinnipiac University national poll puts Sanders a distant second behind Hillary Clinton. He has 15 percent support among Democratic-leaning voters compared to Clinton's 57 percent.

The Democratic field is far less crowded than those seeking the Republican nomination, but Sanders did get additional competition this week when former Maryland Gov. Martin O'Mally joined the race.