Madison, Wisconsin (CNN)Bernie Sanders has been running for president for two months, but Wednesday night in Madison, Wisconsin, his long-shot campaign got real.
When Sanders walked on stage at the Veterans Memorial Coliseum, he was greeted by a raucous, howling crowd of 9,600 people, according to Sanders' campaign aides and arena staff.
A clearly energized Sanders, who late last year was speaking to crowds of 50 people in Iowa classrooms, appeared taken aback by the reception he received.
"Whoa," he said. "In case you haven't noticed, there are a lot of people here."
Sanders' campaign has been organizing the event for weeks, but just recently started telling reporters that 9,000 people signed up to attend.
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"Tonight we have made a little bit of history," he said. "You may know that some 25 candidates are running for president of the United States, but tonight we have more people at a meeting for a candidate for president of the United States than any other candidate has."
Sanders delivered what amounted to his standard stump speech -- a liberal message that pledges to fight for universal health care, break up the biggest banks in the United States and redistribute wealth from the richest Americans to the middle class and poor.
"What I would like to ask of you: Please think big, not small," Sanders said, referring to the audience as his "brothers and sisters."
Calling for a "political revolution," Sanders added, "there is nothing that we cannot accomplish."
Sanders, who is rising in the primary polls and trails only Hillary Clinton, only mentioned the former secretary of state once in his speech.
"This campaign is not about Bernie Sanders, it is not about Hillary Clinton, it is not about anyone else, it is about you," Sanders said to sustained applause.
Sanders worked the rope line after the event -- something the Vermont senator rarely does.
"The message is resonating, not just in Wisconsin, but all over America," Sanders told CNN. "The people are sick and tired of establishment politics, establishment economics. They want real change."
Photos: Bernie Sanders in the spotlight
U.S. Sen. Bernie Sanders, an independent from Vermont, is the longest-serving independent in the history of Congress.
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Photos: Bernie Sanders in the spotlight
Sanders, right, leads a sit-in organized by the Congress of Racial Equality in 1962. The demonstration was staged to oppose housing segregation at the University of Chicago. It was Chicago's first civil rights sit-in.
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Photos: Bernie Sanders in the spotlight
Sanders takes the oath of office to become the mayor of Burlington, Vermont, in 1981. He ran as an independent and won the race by 10 votes.
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Sanders, right, tosses a baseball before a minor-league game in Vermont in 1984. U.S. Sen. Patrick Leahy, center, was also on hand.
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Photos: Bernie Sanders in the spotlight
In 1987, Sanders and a group of Vermont musicians recorded a spoken-word folk album. "We Shall Overcome" was first released as a cassette that sold about 600 copies. When Sanders entered the U.S. presidential race in 2015, the album surged in online sales. But at a CNN town hall, Sanders said, "It's the worst album ever recorded."
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Sanders reads mail at his campaign office in Burlington in 1990. He was running for the U.S. House of Representatives after an unsuccessful bid in 1988.
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In 1990, Sanders defeated U.S. Rep. Peter Smith in the race for Vermont's lone House seat. He won by 16 percentage points.
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Sanders sits next to President Bill Clinton in 1993 before the Congressional Progressive Caucus held a meeting at the White House. Sanders co-founded the caucus in 1991 and served as its first chairman.
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Barack Obama, then a U.S. senator, endorses Sanders' Senate bid at a rally in Burlington in 2006.
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Sanders takes part in a swearing-in ceremony at the U.S. Capitol in January 2007. He won his Senate seat with 65% of the vote.
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Sanders chats with Dr. John Matthew, director of The Health Center in Plainfield, Vermont, in May 2007. Sanders was in Plainfield to celebrate a new source of federal funding for The Health Center.
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Photos: Bernie Sanders in the spotlight
Sanders speaks to reporters in 2010 about the Obama administration's push to extend Bush-era tax cuts. Three days later, Sanders held a filibuster against the reinstatement of the tax cuts. His speech, which lasted more than eight hours, was published in book form in 2011. It is called "The Speech: A Historic Filibuster on Corporate Greed and the Decline of Our Middle Class."
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Sanders and U.S. Rep. Jeff Miller, chairman of the House Committee on Veterans' Affairs, walk to a news conference on Capitol Hill in 2014. Sanders was chairman of the Senate Committee on Veterans' Affairs.
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Photos: Bernie Sanders in the spotlight
In March 2015, Sanders speaks in front of letters and petitions asking Congress to reject proposed cuts to Social Security and Medicare.
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Photos: Bernie Sanders in the spotlight
In July 2015, two months after announcing he would be seeking the Democratic Party's nomination for President, Sanders spoke to nearly 10,000 supporters in Madison, Wisconsin. "Tonight we have made a little bit of history," he said. "You may know that some 25 candidates are running for President of the United States, but tonight we have more people at a meeting for a candidate for President of the United States than any other candidate has."
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Seconds after Sanders took the stage for a campaign rally in August 2015, a dozen protesters from Seattle's Black Lives Matter chapter jumped barricades and grabbed the microphone from the senator. Holding a banner that said "Smash Racism," two of the protesters -- Marissa Johnson, left, and Mara Jacqueline Willaford -- began to address the crowd.
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Sanders shakes hands with Hillary Clinton at a Democratic debate in Las Vegas on October 13. The hand shake came after Sanders' take on the Clinton email scandal. "Let me say something that may not be great politics, but the secretary is right -- and that is that the American people are sick and tired of hearing about the damn emails," Sanders said. "Enough of the emails, let's talk about the real issues facing the United States of America."
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Sanders embraces Remaz Abdelgader, a Muslim student, during an October 2015 event at George Mason University in Fairfax, Virginia. Asked what he would do about Islamophobia in the United States, Sanders said he was determined to fight racism and "build a nation in which we all stand together as one people."
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Sanders waves while walking in a Veterans Day parade in Lebanon, New Hampshire, in November 2015.
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Sanders sits with Killer Mike at the Busy Bee Cafe in Atlanta in November 2015. That evening, the rapper and activist introduced Sanders at a campaign event in the city. "I'm talking about a revolutionary," Killer Mike told supporters. "In my heart of hearts, I truly believe that Sen. Bernie Sanders is the right man to lead this country."
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Comedian Larry David and Sanders appear together on "Saturday Night Live" on February 6. David has taken the role of Sanders in a series of sketches throughout the campaign season.
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Sanders and his wife, Jane, wave to the crowd during a primary night rally in Concord, New Hampshire, on February 9. Sanders defeated Clinton in the New Hampshire primary with 60% of the vote, becoming the first Jewish candidate to win a presidential primary.
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Sanders speaks at a campaign rally in Ann Arbor, Michigan, on March 7. Sanders won the state's primary the next day, an upset that delivered a sharp blow to Clinton's hopes of quickly securing the nomination.
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Sanders speaks at a campaign event in New York's Washington Square Park on April 13.
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Sanders speaks at a rally in Santa Monica, California, on June 7. He pledged to stay in the Democratic race even though Hillary Clinton secured the delegates she needed to become the presumptive nominee.
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Sanders endorses Democratic presidential nominee Hillary Clinton at a rally in Portsmouth, New Hampshire, on July 12.
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Sanders addresses delegates on the first day of the Democratic National Convention in Philadelphia, Pennsylvania, on July 25.
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Sanders brings a giant printout of one of Donald Trump's tweets, in which the President-elect promised not to cut Social Security, Medicare and Medicaid, to a debate at the Senate in Washington on January 4.
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Supporters were impressed by the performance.
"I felt like, this time, I want to be more of a participant in the election than I have been in the past," said Bethany Ragains, 24, who lives in suburban Chicago. "I really felt a connection with Bernie on the issues. He makes me want to get more involved."
Outside the event, Sanders' volunteers handed out stickers, sold t-shirts and, most importantly for the campaign, collected crucial data on each attendee. In addition to registering for the event through the Sanders' website, each person who walked in the door provided the campaign with their name, email, phone number and zip code.
That is new for Sanders' operation; until recently the campaign was not collecting data on people who attended a speech or rally. But now that Sanders is drawing sizable numbers of people to events, his campaign is looking to translate the big turnouts into increased fundraising and an army of volunteers.
Sanders closed his speech on Wednesday with a call to action that received the biggest applause of the night.
"I am more than aware that my opponents will be able to outspend us. But we are going to win this election," Sanders said. "They may have the money, but we have the people. And when the people stand together, we can win."
After the Madison, Sanders heads to Rochester, Minnesota, for another rally.